The Collaborative International Dictionary of English v.0.48:

Shadow \Shad"ow\, v. t. [imp. & p. p. Shadowed; p. pr. & vb.
   n. Shadowing.] [OE. shadowen, AS. sceadwian. See adow,
   n.]
   1. To cut off light from; to put in shade; to shade; to throw
      a shadow upon; to overspead with obscurity.
      [1913 Webster]

            The warlike elf much wondered at this tree,
            So fair and great, that shadowed all the ground.
                                                  --Spenser.
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   2. To conceal; to hide; to screen. [R.]
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            Let every soldier hew him down a bough.
            And bear't before him; thereby shall we shadow
            The numbers of our host.              --Shak.
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   3. To protect; to shelter from danger; to shroud.
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            Shadowing their right under your wings of war.
                                                  --Shak.
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   4. To mark with gradations of light or color; to shade.
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   5. To represent faintly or imperfectly; to adumbrate; hence,
      to represent typically.
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            Augustus is shadowed in the person of [AE]neas.
                                                  --Dryden.
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   6. To cloud; to darken; to cast a gloom over.
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            The shadowed livery of the burnished sun. --Shak.
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            Why sad?
            I must not see the face O love thus shadowed.
                                                  --Beau. & Fl.
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   7. To attend as closely as a shadow; to follow and watch
      closely, especially in a secret or unobserved manner; as,
      a detective shadows a criminal.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Shadow \Shad"ow\ (sh[a^]d"[-o]), n. [Originally the same word as
   shade. [root]162. See Shade.]
   1. Shade within defined limits; obscurity or deprivation of
      light, apparent on a surface, and representing the form of
      the body which intercepts the rays of light; as, the
      shadow of a man, of a tree, or of a tower. See the Note
      under Shade, n., 1.
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   2. Darkness; shade; obscurity.
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            Night's sable shadows from the ocean rise. --Denham.
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   3. A shaded place; shelter; protection; security.
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            In secret shadow from the sunny ray,
            On a sweet bed of lilies softly laid. --Spenser.
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   4. A reflected image, as in a mirror or in water. --Shak.
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   5. That which follows or attends a person or thing like a
      shadow; an inseparable companion; hence, an obsequious
      follower.
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            Sin and her shadow Death.             --Milton.
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   6. A spirit; a ghost; a shade; a phantom. "Hence, horrible
      shadow!" --Shak.
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   7. An imperfect and faint representation; adumbration;
      indistinct image; dim bodying forth; hence, mystical
      representation; type.
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            The law having a shadow of good things to come.
                                                  --Heb. x. 1.
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            [Types] and shadows of that destined seed. --Milton.
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   8. A small degree; a shade. "No variableness, neither shadow
      of turning." --James i. 17.
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   9. An uninvited guest coming with one who is invited. [A
      Latinism] --Nares.
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            I must not have my board pastered with shadows
            That under other men's protection break in
            Without invitement.                   --Massinger.
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   Shadow of death, darkness or gloom like that caused by the
      presence or the impending of death. --Ps. xxiii. 4.
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WordNet (r) 3.0 (2006):

shadow
    n 1: shade within clear boundaries
    2: an unilluminated area; "he moved off into the darkness" [syn:
       darkness, dark, shadow]
    3: something existing in perception only; "a ghostly apparition
       at midnight" [syn: apparition, phantom, phantasm,
       phantasma, fantasm, shadow]
    4: a premonition of something adverse; "a shadow over his
       happiness"
    5: an indication that something has been present; "there wasn't
       a trace of evidence for the claim"; "a tincture of
       condescension" [syn: trace, vestige, tincture,
       shadow]
    6: refuge from danger or observation; "he felt secure in his
       father's shadow"
    7: a dominating and pervasive presence; "he received little
       recognition working in the shadow of his father"
    8: a spy employed to follow someone and report their movements
       [syn: tail, shadow, shadower]
    9: an inseparable companion; "the poor child was his mother's
       shadow"
    v 1: follow, usually without the person's knowledge; "The police
         are shadowing her"
    2: cast a shadow over [syn: shadow, shade, shade off]
    3: make appear small by comparison; "This year's debt dwarfs
       that of last year" [syn: shadow, overshadow, dwarf]

Moby Thesaurus II by Grady Ward, 1.0:

579 Moby Thesaurus words for "shadow":
   Masan, adherent, adumbrate, adumbration, afterglow, afterimage,
   air, airy nothing, alter ego, amount, anima, anima humana,
   apparition, appearance, appendage, apply paint, arrangement,
   astral, astral spirit, atman, atmosphere, attendant, augury,
   auspicate, auspice, awning, ba, balance, banshee, barebones,
   beach umbrella, bean pole, beanstalk, becloud, bedarken, bedaub,
   bedim, bedizen, bedog, befog, begild, begloom, bemist, besmear,
   besmirch, betokening, betokenment, black, black out, blacken,
   blackwash, blight, blind, block the light, blot, blot out, blotch,
   body forth, bosom buddy, breath, breath of life, broomstick, brown,
   brush on paint, brushwork, bubble, buddhi, buff, butt, butt end,
   calcimine, caliber, candle ends, cast, cast a shadow,
   cavaliere servente, chaff, charcoal, chase, chum, clabber up,
   clothes pole, cloud, cloud over, cloud up, coat, color, come after,
   come behind, companion, compass, complexion, complicate,
   composition, comrade, concealment, control, copy, cork, corpse,
   couch, courtier, cover, covering, creep, crony, curse, curtain,
   cut, dab, dangler, dark shade, darken, darken over, darkness, dash,
   daub, dead ringer, debris, deep-dye, defense, degree, demonstrate,
   denigrate, departed spirit, dependent, design, detritus, dim,
   dim out, dimness, dinge, dip, disciple, disembodied spirit,
   distemper, divine breath, dog, double, double-dye, draftsmanship,
   drape, drapery, duplicate, duppy, dusk, dybbuk, dye, ebonize, echo,
   eclipse, effigy, ego, eidolon, emblazon, embody, enamel, encloud,
   encompass with shadow, end, engild, enmist, ether, exact likeness,
   exemplify, extent, eye, face, fag end, fan, fantasy, fast-dye,
   fellow, figure, filings, flunky, fog, follow, follow a clue,
   follow up, follower, following, foreshadow, foreshadowing,
   foreshow, foreshowing, foretoken, foretokening, form, fossil,
   fresco, garble, ghost, gild, glaze, gleam, gloom, gloss, go after,
   go behind, grade, grain, grateful dead, grouping, gruel, guard,
   guide, gumshoe, hanger-on, hant, haunt, have a hunch,
   have an intimation, haze, heart, heel, heeler, height, henchman,
   hint, holdover, homme de cour, hound, hue, hunt down, husks, icon,
   idea, idol, idolum, illuminate, illusion, illustrate, image, imbue,
   immateriality, impersonate, incarnate, incorporeal,
   incorporeal being, incorporeity, indicant, indication, ingrain,
   ink, inner man, interval, intimation, japan, jiva, jivatma, jumble,
   khu, lacquer, lanky, larva, lath, lay on color, lay wait, leap,
   leavings, lee, leftovers, lemures, level, lick, lie in wait,
   light shield, likeness, line, living image, living picture, look,
   lurk, make unintelligible, man, manes, mark, match, mate,
   materialization, measure, melanize, memento, mere shadow, mind,
   miniature, mirror, mirroring, mist, model, move behind, murk,
   mystify, nephesh, nightwalk, nigrify, nose, nose out, notch,
   nuance, nubilate, obfuscate, obnubilate, obscure, obscurity,
   obumbrate, occult, occultate, odds and ends, offscourings, omen,
   oni, orts, outline, overcast, overcloud, overshadow, oversmoke,
   paint, painterliness, paper, parasite, parasol, parget, parings,
   partisan, pas, peg, penumbra, period, personate, personify,
   perspective, phantasm, phantasma, phantasmagoria, phantom,
   photograph, picture, pigment, pitch, plane, plateau, pneuma, point,
   poltergeist, portent, portrait, predict, prefiguration, prefigure,
   preindication, premonitory shiver, premonitory sign,
   premonitory symptom, presage, presence, preservation,
   presignifying, pretypify, prime, prognostic, prognostication,
   project, promise, proportion, protection, protective custody,
   prowl, psyche, public, pursue, pursuer, pursuivant, purusha,
   pussyfoot, rags, rail, rake, range, ratio, rattlebones, reach,
   realize, reflect, reflection, reflex, refuge, refuse, relic,
   relics, remainder, remains, remnant, remove, resemblance, residue,
   residuum, rest, retainer, revenant, roach, round, ruach, rubbing,
   rubbish, ruins, rump, run down, run to earth, rung, safekeeping,
   safety, satellite, sawdust, scale, scintilla, scope, scourings,
   scramble, scraps, screen, sectary, semblance, servant, shade,
   shaded, shader, shadiness, shading, shadow forth,
   shadows numberless, shadowy, shady, shape, shaving, shavings,
   shellac, shelter, shield, shrouded spirit, sidekick, sign,
   silhouette, similitude, simulacrum, sip, skeleton, skiagram,
   skiagraph, skulk, slat, slim, slink, slip, slop on paint, smack,
   smattering, smear, smell, smell out, smirch, smog, smoke, smudge,
   smut, smutch, sneak, sniff out, somber, soot, soothsay, soul, soup,
   soupcon, space, spark, specter, spectral ghost, spindlelegs,
   spindleshanks, spirit, spiritual being, spiritus, spit and image,
   spitting image, splinter, spook, sprinkling, sprite,
   stack of bones, stain, stair, stalk, standard, steal, step, stilt,
   stint, stipple, stooge, straw, streak, string along, stubble,
   stump, successor, suggestion, sunblind, sunshade, sup, supporter,
   survival, suspicion, sweepings, tag, tag after, tag along, tagtail,
   tail, tailgate, taste, technique, the self, theophany, thin air,
   thought, tinct, tincture, tinge, tint, tiptoe, token, tokening,
   tone, touch, trace, trace down, tracing, track, track down, trail,
   trail after, trainbearer, tread, tread close upon, treatment,
   twiggy, twin, type, umbra, umbrage, umbrageousness, umbrella,
   undercoat, unsubstantiality, values, vapor, varnish, veil, vein,
   very image, very picture, vestige, vision, votary, wafer,
   waking dream, walking dead man, wandering soul, ward heeler, wash,
   waste, watchful eye, whitewash, wildest dream, wraith, zombie



The Free On-line Dictionary of Computing (30 December 2018):

SHADOW

    A syntax-directed compiler written by Barnett
   and Futrelle in 1962.  It was the predecessor to SNOBOL(?)

   [Sammet 1969, p. 448, 605].

   (1995-01-16)


Easton's 1897 Bible Dictionary:

Shadow
   used in Col. 2:17; Heb. 8:5; 10:1 to denote the typical relation
   of the Jewish to the Christian dispensation.