The Collaborative International Dictionary of English v.0.48:

Decamp \De*camp"\, v. i. [imp. & p. p. Decamped (?; 215); p.
   pr. & vb. n. Decamping.] [F. d['e]camper; pref. d['e]- (L.
   dis) + camp camp. See Camp.]
   1. To break up a camp; to move away from a camping ground,
      usually by night or secretly. --Macaulay.
      [1913 Webster]

   2. Hence, to depart suddenly; to run away; -- generally used
      disparagingly.
      [1913 Webster]

            The fathers were ordered to decamp, and the house
            was once again converted into a tavern. --Goldsmith.
      [1913 Webster]

WordNet (r) 3.0 (2006):

decamp
    v 1: leave a camp; "The hikers decamped before dawn" [syn:
         decamp, break camp]
    2: run away; usually includes taking something or somebody
       along; "The thief made off with our silver"; "the accountant
       absconded with the cash from the safe" [syn: abscond,
       bolt, absquatulate, decamp, run off, go off, make
       off]
    3: leave suddenly; "She persuaded him to decamp"; "skip town"
       [syn: decamp, skip, vamoose]

Moby Thesaurus II by Grady Ward, 1.0:

60 Moby Thesaurus words for "decamp":
   abscond, absquatulate, avoid, beat a retreat, begone, bolt, break,
   break camp, clear out, cut and run, depart, desert, dog it, elope,
   elude, escape, evade, exit, flee, fly, fugitate, go, go AWOL,
   hightail, jump, jump bail, kite, lam, leave, levant, make off,
   powder, pull up stakes, quit, retire, run, run away, run away from,
   run away with, run for it, run off, scape, scram, show the heels,
   shun, skedaddle, skip, skip out, slip the cable, split,
   strike camp, take French leave, take a powder, take flight,
   take off, take to flight, take wing, turn tail, vamoose,
   withdraw