Source : Webster's Revised Unabridged Dictionary (1913)

Deploy \De*ploy"\, v. t. & i. [imp. & p. p. {Deployed}; p. pr. &
   vb. n. {Deploying}.] [F. d['e]ployer; pref. d['e]? = d['e]s
   (L. dis) + ployer, equiv. to plier to fold, fr. L. plicare.
   See {Ply}, and cf. {Display}.] (Mil.)
   To open out; to unfold; to spread out (a body of troops) in
   such a way that they shall display a wider front and less
   depth; -- the reverse of ploy; as, to deploy a column of
   troops into line of battle.