flank / flangk/ • n. 1. the side of a person's or animal's body between the ribs and the hip: leaning against his horse's flanks. ∎  a cut of meat from such a part of an animal: a thick flank of beef on a spit | two pounds of flank. ∎  the side of something large, such as a mountain, building, or ship: the northern flank of the volcano.2. the right or left side of a body of people such as an army, a naval force, or a soccer team: the left flank of the Russian Third Army. ∎  the right or left side of a game board such as a chessboard.• v. [tr.] (often be flanked) be situated on each side of or on one side of (someone or something): the fireplace is flanked by built-in bookshelves. ∎  [usu. as adj.] (flanking) guard or strengthen (a military force or position) from the side: massive walls, defended by four flanking towers. ∎  [usu. as adj.] (flanking) attack down or from the sides, or rake with gunfire from the sides: a flanking attack from the northeast.

flank.
1. Lateral face of a structure: an end or side as distinguished from the front or back (e.g. side of a bastion).

2. Party-wall between terrace-houses.

3. Haunch of an arch.

4. Valley of a roof.

flank side of the body of an animal XII; side of an army XVI. — (O)F. flanc — Frank. *hlanca side; cf. FLINCH, LINK1.