Flank may refer to:
* Flank, the side of either a horse or a military unit
* Flanking maneuver in military tactics
* Flank, a region of the posterior torso (lower back) beneath the ribs and above the ilium
* Flank, a specific position in rugby union, Australian rules football and American football
* Flank steak, a specific cut of beef
* Flank speed, the maximum possible speed of a ship, faster than full speed