The Collaborative International Dictionary of English v.0.48:

Cloak \Cloak\ (kl[=o]k; 110), n. [Of. cloque cloak (from the
   bell-like shape), bell, F. cloche bell; perh. of Celtic
   origin and the same word as E. clock. See 1st Clock.]
   1. A loose outer garment, extending from the neck downwards,
      and commonly without sleeves. It is longer than a cape,
      and is worn both by men and by women.
      [1913 Webster]

   2. That which conceals; a disguise or pretext; an excuse; a
      fair pretense; a mask; a cover.
      [1913 Webster]

            No man is esteemed any ways considerable for policy
            who wears religion otherwise than as a cloak.
                                                  --South.
      [1913 Webster]

   Cloak bag, a bag in which a cloak or other clothes are
      carried; a portmanteau. --Shak.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Cloak \Cloak\, v. t. [imp. & p. p. Cloaked; p. pr. & vb. n.
   Cloaking.]
   To cover with, or as with, a cloak; hence, to hide or
   conceal.
   [1913 Webster]

         Now glooming sadly, so to cloak her matter. --Spenser.

   Syn: See Palliate.
        [1913 Webster]

WordNet (r) 3.0 (2006):

cloak
    n 1: anything that covers or conceals
    2: a loose outer garment
    v 1: hide under a false appearance; "He masked his
         disappointment" [syn: dissemble, cloak, mask]
    2: cover as if with clothing; "the mountain was clothed in
       tropical trees" [syn: clothe, cloak, drape, robe]
    3: cover with or as if with a cloak; "cloaked monks"

Moby Thesaurus II by Grady Ward, 1.0:

148 Moby Thesaurus words for "cloak":
   alibi, apology, apply to, arm, armor, becloud, befog, blanket,
   bless, blind, block, bonnet, boot, breech, camouflage, canopy, cap,
   cape, champion, clothe, cloud, coat, coif, color, compass about,
   conceal, concealment, cope, copyright, cover, cover story,
   cover up, cover-up, coverage, covering, covert, coverture, cowl,
   cowling, curtain, cushion, defend, device, disguise, dissemble,
   dissimulate, distract attention from, drape, drapery, dress up,
   eclipse, ensconce, enshroud, ensure, envelop, excuse, facade, face,
   feint, fence, fend, film, frock, front, gloss, gloss over, gown,
   guarantee, guard, guise, handle, hanging, harbor, hat, haven, hide,
   hood, housing, insure, jacket, keep, keep from harm,
   keep under cover, lame excuse, lay on, lay over, locus standi,
   make safe, mantle, mask, muffle, nestle, obduce, obfuscate,
   obscure, occult, ostensible motive, overcoat, overlay, overspread,
   pall, patent, police, poncho, poor excuse, pretense, pretension,
   pretext, protect, protestation, public motive, put on, put-off,
   refuge, register, ride shotgun for, robe, safeguard, screen, scum,
   secure, semblance, shade, sham, shelter, shield, shirt, shoe, show,
   shroud, slur over, smoke screen, sock, spread over, stalking-horse,
   stocking, stratagem, subterfuge, superimpose, superpose, trick,
   underwrite, varnish, veil, veneer, vestment, whitewash, wrap



Easton's 1897 Bible Dictionary:

Cloak
   an upper garment, "an exterior tunic, wide and long, reaching to
   the ankles, but without sleeves" (Isa. 59:17). The word so
   rendered is elsewhere rendered "robe" or "mantle." It was worn
   by the high priest under the ephod (Ex. 28:31), by kings and
   others of rank (1 Sam. 15:27; Job 1:20; 2:12), and by women (2
   Sam. 13:18).

     The word translated "cloke", i.e., outer garment, in Matt.
   5:40 is in its plural form used of garments in general (Matt.
   17:2; 26:65). The cloak mentioned here and in Luke 6:29 was the
   Greek himation, Latin pallium, and consisted of a large square
   piece of wollen cloth fastened round the shoulders, like the
   abba of the Arabs. This could be taken by a creditor (Ex.
   22:26,27), but the coat or tunic (Gr. chiton) mentioned in Matt.
   5:40 could not.

     The cloak which Paul "left at Troas" (2 Tim. 4:13) was the
   Roman paenula, a thick upper garment used chiefly in travelling
   as a protection from the weather. Some, however, have supposed
   that what Paul meant was a travelling-bag. In the Syriac version
   the word used means a bookcase. (See Dress.)