The Collaborative International Dictionary of English v.0.48:

Cover \Cov"er\ (k?v"?r), n.
   1. Anything which is laid, set, or spread, upon, about, or
      over, another thing; an envelope; a lid; as, the cover of
      a book.
      [1913 Webster]

   2. Anything which veils or conceals; a screen; disguise; a
      cloak. "Under cover of the night." -- Macaulay.
      [1913 Webster]

            A handsome cover for imperfections.   --Collier.
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   3. Shelter; protection; as, the troops fought under cover of
      the batteries; the woods afforded a good cover.
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            Being compelled to lodge in the field . . . whilst
            his army was under cover, they might be forced to
            retire.                               --Clarendon.
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   4. (Hunting) The woods, underbrush, etc., which shelter and
      conceal game; covert; as, to beat a cover; to ride to
      cover.
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   5. That portion of a slate, tile, or shingle, which is hidden
      by the overlap of the course above. --Knight.
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   6. (Steam Engine) The lap of a slide valve.
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   7. [Cf. F. couvert.] A tablecloth, and the other table
      furniture; esp., the table furniture for the use of one
      person at a meal; as, covers were laid for fifty guests.
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   To break cover, to start from a covert or lair; -- said of
      game.

   Under cover, in an envelope, or within a letter; -- said of
      a written message.
      [1913 Webster]

            Letters . . . dispatched under cover to her
            ladyship.                             --Thackeray.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Cover \Cov"er\ (k?v"?r), v. t. [imp. & p. p. Covered (-?rd);
   p. pr. & vb. n. Covering.] [OF. covrir, F. couvrir, fr. L.
   cooperire; co- + operire to cover; probably fr. ob towards,
   over + the root appearing in aperire to open. Cf. Aperient,
   Overt, Curfew.]
   1. To overspread the surface of (one thing) with another; as,
      to cover wood with paint or lacquer; to cover a table with
      a cloth.
      [1913 Webster]

   2. To envelop; to clothe, as with a mantle or cloak.
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            And with the majesty of darkness round
            Covers his throne.                    --Milton.
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            All that beauty than doth cover thee. --Shak.
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   3. To invest (one's self with something); to bring upon
      (one's self); as, he covered himself with glory.
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            The powers that covered themselves with everlasting
            infamy by the partition of Poland.    --Brougham.
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   4. To hide sight; to conceal; to cloak; as, the enemy were
      covered from our sight by the woods.
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            A cloud covered the mount.            --Exod. xxiv.
                                                  15.
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            In vain shou striv'st to cover shame with shame.
                                                  --Milton.
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   5. To brood or sit on; to incubate.
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            While the hen is covering her eggs, the male . . .
            diverts her with his songs.           --Addison.
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   6. To overwhelm; to spread over.
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            The waters returned and covered the chariots and the
            horsemen.                             --Ex. xiv. 28.
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   7. To shelter, as from evil or danger; to protect; to defend;
      as, the cavalry covered the retreat.
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            His calm and blameless life
            Does with substantial blessedness abound,
            And the soft wings of peace cover him round.
                                                  --Cowley.
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   8. To remove from remembrance; to put away; to remit.
      "Blessed is he whose is covered." --Ps. xxxii. 1.
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   9. To extend over; to be sufficient for; to comprehend,
      include, or embrace; to account for or solve; to
      counterbalance; as, a mortgage which fully covers a sum
      loaned on it; a law which covers all possible cases of a
      crime; receipts than do not cover expenses.
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   10. To put the usual covering or headdress on.
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             Cover thy head . . .; nay, prithee, be covered.
                                                  --Shak.
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   11. To copulate with (a female); to serve; as, a horse covers
       a mare; -- said of the male.
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   To cover ground or To cover distance, to pass over; as,
      the rider covered the ground in an hour.

   To cover one's short contracts (Stock Exchange), to buy
      stock when the market rises, as a dealer who has sold
      short does in order to protect himself.

   Covering party (Mil.), a detachment of troops sent for the
      protection of another detachment, as of men working in the
      trenches.

   To cover into, to transfer to; as, to cover into the
      treasury.

   Syn: To shelter; screen; shield; hide; overspread.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Cover \Cov"er\, v. i.
   To spread a table for a meal; to prepare a banquet. [Obs.]
   --Shak.
   [1913 Webster]

WordNet (r) 3.0 (2006):

cover
    n 1: a covering that serves to conceal or shelter something; "a
         screen of trees afforded privacy"; "under cover of
         darkness"; "the brush provided a covert for game"; "the
         simplest concealment is to match perfectly the color of the
         background" [syn: screen, cover, covert,
         concealment]
    2: bedding that keeps a person warm in bed; "he pulled the
       covers over his head and went to sleep" [syn: blanket,
       cover]
    3: the act of concealing the existence of something by
       obstructing the view of it; "the cover concealed their guns
       from enemy aircraft" [syn: cover, covering, screening,
       masking]
    4: the protective covering on the front, back, and spine of a
       book; "the book had a leather binding" [syn: binding, book
       binding, cover, back]
    5: a natural object that covers or envelops; "under a covering
       of dust"; "the fox was flushed from its cover" [syn:
       covering, natural covering, cover]
    6: covering for a hole (especially a hole in the top of a
       container); "he removed the top of the carton"; "he couldn't
       get the top off of the bottle"; "put the cover back on the
       kettle" [syn: top, cover]
    7: fire that makes it difficult for the enemy to fire on your
       own individuals or formations; "artillery provided covering
       fire for the withdrawal" [syn: cover, covering fire]
    8: a fixed charge by a restaurant or nightclub over and above
       the charge for food and drink [syn: cover charge, cover]
    9: a recording of a song that was first recorded or made popular
       by somebody else; "they made a cover of a Beatles' song"
       [syn: cover, cover version, cover song]
    10: a false identity and background (especially one created for
        an undercover agent); "her new name and passport are cover
        for her next assignment"
    v 1: provide with a covering or cause to be covered; "cover her
         face with a handkerchief"; "cover the child with a
         blanket"; "cover the grave with flowers" [ant: expose,
         uncover]
    2: form a cover over; "The grass covered the grave" [syn:
       cover, spread over]
    3: span an interval of distance, space or time; "The war
       extended over five years"; "The period covered the turn of
       the century"; "My land extends over the hills on the
       horizon"; "This farm covers some 200 acres"; "The Archipelago
       continues for another 500 miles" [syn: cover, continue,
       extend]
    4: provide for; "The grant doesn't cover my salary"
    5: act on verbally or in some form of artistic expression; "This
       book deals with incest"; "The course covered all of Western
       Civilization"; "The new book treats the history of China"
       [syn: cover, treat, handle, plow, deal, address]
    6: include in scope; include as part of something broader; have
       as one's sphere or territory; "This group encompasses a wide
       range of people from different backgrounds"; "this should
       cover everyone in the group" [syn: embrace, encompass,
       comprehend, cover]
    7: travel across or pass over; "The caravan covered almost 100
       miles each day" [syn: traverse, track, cover, cross,
       pass over, get over, get across, cut through, cut
       across]
    8: be responsible for reporting the details of, as in
       journalism; "Snow reported on China in the 1950's"; "The cub
       reporter covered New York City" [syn: report, cover]
    9: hold within range of an aimed firearm
    10: to take an action to protect against future problems; "Count
        the cash in the drawer twice just to cover yourself"
    11: hide from view or knowledge; "The President covered the fact
        that he bugged the offices in the White House" [syn:
        cover, cover up]
    12: protect or defend (a position in a game); "he covered left
        field"
    13: maintain a check on; especially by patrolling; "The second
        officer covered the top floor"
    14: protect by insurance; "The insurance won't cover this" [syn:
        cover, insure, underwrite]
    15: make up for shortcomings or a feeling of inferiority by
        exaggerating good qualities; "he is compensating for being a
        bad father" [syn: cover, compensate, overcompensate]
    16: invest with a large or excessive amount of something; "She
        covered herself with glory"
    17: help out by taking someone's place and temporarily assuming
        his responsibilities; "She is covering for our secretary who
        is ill this week"
    18: be sufficient to meet, defray, or offset the charge or cost
        of; "Is this enough to cover the check?"
    19: spread over a surface to conceal or protect; "This paint
        covers well"
    20: cover as if with a shroud; "The origins of this civilization
        are shrouded in mystery" [syn: shroud, enshroud, hide,
        cover]
    21: copulate with a female, used especially of horses; "The
        horse covers the mare" [syn: breed, cover]
    22: put something on top of something else; "cover the meat with
        a lot of gravy" [syn: overlay, cover]
    23: play a higher card than the one previously played; "Smith
        covered again"
    24: be responsible for guarding an opponent in a game
    25: sit on (eggs); "Birds brood"; "The female covers the eggs"
        [syn: brood, hatch, cover, incubate]
    26: clothe, as if for protection from the elements; "cover your
        head!" [syn: cover, wrap up]

Moby Thesaurus II by Grady Ward, 1.0:

733 Moby Thesaurus words for "cover":
   American plan, European plan, Smyth sewing, a la carte, abri,
   account for, accouple, accumulate, act, admit, afghan, agglutinate,
   air cover, air raid, air support, air-raid shelter, alibi,
   altar carpet, altar cloth, alternate, amass, ante, ante up,
   antepast, antimacassar, apology, apply paint, apply to, arm, armor,
   articulate, assemble, assimilate, associate, asylum, atone, attire,
   awning, back, backing, baldachin, ball, band, bang, bar, barricade,
   batten, batten down, be gravid, be intimate, be knocked up,
   be pregnant, be with child, beach umbrella, becloud, bed linen,
   bedaub, bedclothes, bedcover, bedding, bedizen, bedsheet,
   bedspread, befog, begild, besmear, bespread, bet, bet on,
   bibliopegy, bind, binder board, binding, blanket, bless, blind,
   block, block up, blockade, boards, boil, bolt-hole, bomb shelter,
   bombing, bombproof, bond, book cloth, book cover, book jacket,
   bookbinding, bookcase, bracket, breed, bridge, bridge over, broil,
   brood, brush on paint, buffalo robe, bulwark, bung, bunker, bury,
   button, button up, cache, calcimine, call, camouflage, canopy, cap,
   carpet, carry, carry young, case, casemaking, casing-in, casserole,
   caulk, cave, cement, centerpiece, cerecloth, cerement, chain,
   champion, chink, choke, choke off, choke up, chrismal, ciborium,
   clap, clap together, cloak, clock, clog, clog up, close, close up,
   cloth, clothe, clothes, cloud, coat, cohabit, collating,
   collating mark, collect, color, combine, come together, comfort,
   comforter, command, commit adultery, compass about, compensate,
   compensate for, complete, complexion, comprehend, comprise,
   concatenate, conceal, concealment, congest, conglobulate, conjoin,
   conjugate, connect, constipate, constrict, contain, contour sheet,
   contract, cope, copulate, copyright, cork, corner, corporal,
   count in, counter, counterbalance, counterpane, couple, course,
   couvert, cover charge, cover story, cover up, cover-up, coverage,
   covering, coverlet, coverlid, covers, covert, coverture, cowl,
   cowling, cozy, cranny, cross, crown, cubby, cubbyhole,
   culinary masterpiece, culinary preparation, curtain, cushion,
   cyclone cellar, dab, dam, dam up, dark corner, daub, deal with,
   deck, deep-dye, defend, defense, defray, den, dessert, device,
   diddle, dip, disguise, dish, dissemble, distemper,
   distract attention from, ditch, do, do a hitch, do a stint,
   do a tour, do penance, do time, doily, dossal, double, double-dye,
   drape, drapery, draw the curtains, dress, dry run, dugout,
   dust cover, dust jacket, dye, earth, eclipse, eiderdown, emblazon,
   embody, embrace, enamel, encircle, enclose, encompass, enfold,
   engild, engulf, enlist, ensconce, enshroud, ensure, entree,
   entremets, envelop, environ, envisage, excuse, expiate, extend,
   extend over, eye, facade, face, fade, fallout shelter, false front,
   fanon, fast-dye, fasten, feint, fence, fend, fill, fill in,
   fill in for, fill out, fill up, film, fingerstall, fitted sheet,
   floor, floor covering, flooring, fold, fold up, folding, footband,
   fornicate, foul, foxhole, fresco, frig, front, fry, funk hole,
   gamble, garb, gather, gathering, gestate, gild, give and take,
   glaze, gloss, gloss over, glue, gluing-off, go, go out, go over,
   grain, grill, ground, grow over, guarantee, guard, guise, handle,
   hanging, harbor, harborage, hard binding, hatch, have a go,
   have sex, have sexual relations, have tenure, haven, hazard,
   headband, help, helping, hide, hideaway, hideout, hidey hole,
   hiding, hiding place, hold, hold office, hole, hood, housing, hue,
   illuminate, imbue, include, incorporate, incubate, indemnify,
   ingrain, insure, inundate, jacket, jalousie, jam, japan, join,
   keep, keep a watch, keep from harm, keep under cover, key, knot,
   lacquer, lair, lame excuse, lap robe, latch, lay, lay a wager,
   lay down, lay on, lay on color, lay over, lay together, layer,
   league, lee, library binding, lid, lie, lie on, lie with,
   light shield, linen, lining, lining-up, link, lock, lock out,
   lock up, locus standi, lump together, main dish, make a bet,
   make amends, make compensation, make good, make it with, make love,
   make out, make safe, make up for, mantle, marquee, marquise, marry,
   marshal, mask, masquerade, mass, mate, measure, mechanical binding,
   meet a bet, merge, milk run, mission, mobilize, mount, muffle,
   nestle, niche, niggerhead, nook, number among, obduce, obfuscate,
   obscure, obstipate, obstruct, occlude, occult, occupy, offset,
   operculum, ordinary, ostensible motive, overcast, overgrow,
   overlay, overlie, overpass, overshadow, overspread, pack, padlock,
   paint, pair, pall, parasol, parget, parlay, parquet, pass,
   pass over, pass through, patchwork quilt, patent, patrol, pave,
   pavement, pavilion, paving, pay back, perambulate, peregrinate,
   pererrate, perfect binding, piece together, pigment, pillow slip,
   pillowcase, place, plastic binding, plate, play against, pledget,
   plug, plug up, plumb, plunge, ply, police, poor excuse, port,
   portion, preservation, pretense, pretension, pretext, prime,
   protect, protection, protective custody, protestation, provide for,
   public motive, punt, purdah, put on, put together, put-off, put-on,
   quilt, range, range over, re-up, reach, reach out, receive, recess,
   reckon among, reckon in, reckon with, recompense, reconnaissance,
   reconnaissance mission, reconnoiter, rectify, reenlist, refuge,
   register, relieve, repay, retaliate, retreat, ride shotgun for,
   roast, robe, roll into one, rounding, rug, run, run riot,
   saddle stitching, safeguard, safekeeping, safety, safety zone,
   sanctuary, scarf, scour, scour the country, scout, scramble,
   screen, screw, scum, seal, seal off, seal up, second helping,
   secret place, secrete, secure, security, see, self-service,
   semblance, serve, serve time, service, serving, set, set right,
   sewing, shade, shader, shadow, sham, sheathe, sheet, sheeting,
   shellac, shelter, shield, show, shroud, shut, shut the door,
   shut up, shutter, shuttle raid, side dish, side sewing, sign up,
   signature, sit, sit in, slam, sleep with, slip, slipcase,
   slipcover, slop on paint, slur over, smashing, smear, smoke screen,
   snap, soft binding, solder, sortie, span, spell, spell off, spile,
   spiral binding, splice, spread, spread over, squeeze shut, stain,
   stake, stalking-horse, stamping, stanch, stand in, stand pat,
   stapling, stash, stay, stench, stick together, stipple, stop,
   stop up, stopper, stopple, storm cave, storm cellar, straddle,
   strafing, strangle, stratagem, stretch, stretch out, stuff,
   stuff up, submerge, substitute, subterfuge, sunblind, sunshade,
   superimpose, superpose, surfacing, surround, swaddle, swarm over,
   sweep, tablecloth, tailband, take charge, take in,
   take into account, take into consideration, take over, take turns,
   take up, tape, tarpaulin, teem over, terra firma, tester,
   thrust out, tidy, tie, time off, tinct, tincture, tinge, tint,
   tipping, tone, top, track, training mission, transit, travel,
   travel over, travel through, traverse, trench, trick, trimming,
   umbrella, undercoat, undercovert, underwrite, unify, unite,
   varnish, veil, veiling, venetian blind, vestment, voyage, wager,
   wash, watchful eye, weld, whitewash, window shade, wire stitching,
   wrap, wrapper, wraps, yoke, zip up, zipper