Either of the two divisions (right wing, n. adj., left wing, n. adj.) on each side of the main body or centre of an army or fleet in battle array…

Each of the two wings of an army.

A wing or flank of an army.

Military. The extreme left or right side of an army or body of men in military formation; a wing. †a flank (see also aflank, adv.), in flank: at the…

The front or leading edge of a group. A wing of a fleet or army. Obsolete.

Military. A body of troops placed on the flanks of an army, battalion, etc.; a wing or flank. Obsolete.

Military. The left wing or flank of an army; the left-hand side of a military formation. Also in plural: the soldiers whose place is on the left.

The right wing or flank of an army, etc.; the right-hand end of a line of troops.

the outer flank of a wheeling body of troops, being furthest from the pivot (pivot, n. 4).

That wheels, in various senses. Military. (See wheel, v. 3) wheeling flank, the outward flank in wheeling, which describes the largest curve.