The Collaborative International Dictionary of English v.0.48:

Bunk \Bunk\ (b[u^][ng]k), n. [Cf. OSw. bunke heap, also boaring,
   flooring. Cf. Bunch.]
   1. A wooden case or box, which serves for a seat in the
      daytime and for a bed at night. [U.S.]
      [1913 Webster]

   2. One of a series of berths or bed places in tiers; as, to
      sleep in the top bunk.
      [1913 Webster]

   3. A piece of wood placed on a lumberman's sled to sustain
      the end of heavy timbers. [Local, U.S.]
      [1913 Webster]

   4. a bed. [informal]
      [PJC]

The Collaborative International Dictionary of English v.0.48:

Bunk \Bunk\, v. i. [imp. & p. p. Bunked; p. pr. & vb. n.
   Bunking.]
   To go to bed in a bunk; -- sometimes with in. [Colloq. U.S.]
   --Bartlett.
   [1913 Webster]

WordNet (r) 3.0 (2006):

bunk
    n 1: a long trough for feeding cattle [syn: bunk, feed bunk]
    2: a bed on a ship or train; usually in tiers [syn: berth,
       bunk, built in bed]
    3: a rough bed (as at a campsite)
    4: unacceptable behavior (especially ludicrously false
       statements) [syn: bunk, bunkum, buncombe, guff,
       rot, hogwash]
    5: a message that seems to convey no meaning [syn: nonsense,
       bunk, nonsensicality, meaninglessness, hokum]
    6: beds built one above the other [syn: bunk bed, bunk]
    v 1: avoid paying; "beat the subway fare" [syn: beat, bunk]
    2: provide with a bunk; "We bunked the children upstairs"
    3: flee; take to one's heels; cut and run; "If you see this man,
       run!"; "The burglars escaped before the police showed up"
       [syn: scat, run, scarper, turn tail, lam, run
       away, hightail it, bunk, head for the hills, take to
       the woods, escape, fly the coop, break away]