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"