\Flank\ (fl[a^][ng]k), n. [F. flanc, prob. fr. L. flaccus
flabby, with n inserted. Cf. {Flaccid}, {Flanch}, {Flange}.]
1. The fleshy or muscular part of the side of an animal,
   between the ribs and the hip. See Illust. of {Beef}.
2. (Mil.)
   (a) 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.
             When to right and left the front
             Divided, and to either flank retired. --Milton.
   (b) (Fort.) 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. See Illust. of {Bastion}.
3. (Arch.) The side of any building. --Brands.
4. That part of the acting surface of a gear wheel tooth that
   lies within the pitch line.
{Flank attack} (Mil.), an attack upon the side of an army or
   body of troops, distinguished from one upon its front or
   rear.
{Flank company} (Mil.), a certain number of troops drawn up
   on the right or left of a battalion; usually grenadiers,
   light infantry, or riflemen.
{Flank defense} (Fort.), protection of a work against undue
   exposure to an enemy's direct fire, by means of the fire
   from other works, sweeping the ground in its front.
{Flank en potence} (Mil.), any part of the right or left wing
   formed at a projecting angle with the line.
{Flank files}, the first men on the right, and the last on
   the left, of a company, battalion, etc.
{Flank march}, a march made parallel or obliquely to an
   enemy's position, in order to turn it or to attack him on
   the flank.
{Flank movement}, a change of march by an army, or portion of
   one, in order to turn one or both wings of the enemy, or
   to take up a new position.
{Flanks of a frontier}, salient points in a national
   boundary, strengthened to protect the frontier against
   hostile incursion.
{Flank patrol}, detachments acting independently of the
   column of an army, but patrolling along its flanks, to
   secure it against surprise and to observe the movements of
   the enemy.

\Flank\ (fl[a^][ng]k), v. t. [imp. & p. p. {Flanked}
(fl[a^][ng]kt); p. pr. & vb. n. {Flanking}.] [Cf. F.
flanquer. See {Flank}, n., and cf. {Flanker}, v. t.]
1. To stand at the flank or side of; to border upon.
         Stately colonnades are flanked with trees. --Pitt.
2. 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.

\Flank\, v. i.
1. To border; to touch. --Bp. Butler.
2. To be posted on the side.