The side of an army, or of any division of an army, as of a
brigade, regiment, or battalion; the extreme right or left; as, to
attack an enemy in flank is to attack him on the side.

That part of a bastion which reaches from the curtain to the
face, and defends the curtain, the flank and face of the opposite
bastion; any part of a work defending another by a fire along the
outside of its parapet.

The side of any building.

That part of the acting surface of a gear wheel tooth that
lies within the pitch line.

To stand at the flank or side of; to border upon.

To overlook or command the flank of; to secure or guard
the flank of; to pass around or turn the flank of; to attack, or
threaten to attack; the flank of.

To border; to touch.

To be posted on the side.