From Longman Dictionary of Contemporary Englishobservation postˌobserˈvation ˌpost noun [countable] PMa position from which an enemy can be watched
Examples from the Corpus
observation post• It was some kind of an observation post or mast.• There could be other events, like the flamethrower attack on an observation post farther along the border.• Capt. Warr found an excellent observation post, but our party was not so successful.• The bright red Infobox, a temporary three-story structure, provides a handy observation post.• He had found the observation post two miles beyond the outer rim of the Jabal Hamrin. 