WordNet sense 1 (the side of military or naval formation):

flank

WordNet sense 2 (a stage area out of sight of the audience):

backstage, offstage

WordNet sense 3 (a barrier that surrounds the wheels of a vehicle to block splashing water or mud):

fender

WordNet sense 4 (an addition that extends a main building):

annex, extension, annexe, annex

WordNet sense 5 (travel through the air; be airborne):

fly