Flanker

Webster's Dictionary of the English Language

·vt To attack sideways.

II. Flanker ·vt To defend by lateral fortifications.

III. Flanker ·noun One who, or that which, flanks, as a skirmisher or a body of troops sent out upon the flanks of an army toguard a line of march, or a fort projecting so as to command the side of an assailing body.