n. The posterior part of either side of an animal, between the ribs and the hip; also, the thin piece of flesh constituting this part.n. In entomology, the pleura or side of an insect's thorax.n. Milit., one of the sides of an army, or of any of its divisions, as a brigade, regiment, or battalion: as, to attack the enemy on the right flank.n. Hence A side of anything: as, the flanks of a building.n. In fortification, that part of a bastion which reaches from the curtain to the face, or any part of a work that defends another work by a fire along the outside of its parapet. See cut under bastion.n. The acting surface of a cog inside the pitch-line.n. plural In farriery, a wrench or any other injury to the back of a horse.n. In leather manufacturing, the part of a hide from the side of a beast.Pertaining to a flank or side.To stand or be placed or posted at the flank or side of; border at the side or sides: as, the flanking troops of an army.Specifically Milit.: To attack or threaten the side or flank of; place troops so as to command, threaten, or attack the flank of.To pass round or turn the flank of; march or move along or past one side of, as an opposing army.To secure or guard the flank of: as, they flanked their position with abattis.To occupy a flank position; border; touch: with on.n. A spark or flake of fire.