Source : Webster's Revised Unabridged Dictionary (1913)

Outpost \Out"post`\, n. (Mil.)
   (a) A post or station without the limits of a camp, or at a
       distance from the main body of an army, for observation
       of the enemy.
   (b) The troops placed at such a station.

Source : WordNet®

outpost
     n 1: a station in a remote or sparsely populated location [syn: {outstation}]
     2: a settlement on the frontier of civilization [syn: {frontier
        settlement}]
     3: a military post stationed at a distance from the main body
        of troops