Other forms: flanked, flanks, flanking
A flank is a side. On an animal it is the stretch between the ribs and the hip — the flank of a horse, warm under your hand — and on an army it is the left or right edge of the line.
The military sense carries the most weight, because your flanks are where you are weakest: armies protect them, turn them, and attack from the flank rather than head-on. Sport took the whole idea over, and a winger runs down the left flank. As a verb, to flank is to stand on either side of something — two police officers flanked the door, the drive was flanked by lime trees — and it turns up in the passive far more than the active. Butchers use flank for the cut of meat from the animal's side, sold as flank steak. Nothing in the word is emotional; it names a position.
1nounribsThe side of an animal or person, between the ribs and the hip.
“The horse's flank was dark with sweat.”
synonyms: side
2nounflankThe left or right side of an army, a formation or a sports team.
“The attack came from the left flank at first light.”
3verbstandTo stand or be placed on both sides of someone or something.
“Two guards flanked the entrance to the hall.”
4nouncutA cut of meat from the side of an animal.
“He bought a piece of flank and left it in a marinade overnight.”
flank is a side.
Flank came through Old French flanc, probably from Frankish hlanca, and behind that Proto-Germanic hlankaz — flexible, sleek, bending. The root is kleng-, to bend, and the same family gives English lank. The flank is named for the place where the body bends.
Proto-Indo-European
*kleng- — to bend
Proto-Germanic
*hlankaz — flexible, sleek, bendsome
Proto-West Germanic
*hlanku — bend, curve, hip, flank
Frankish
*hlanca
Old French
flanc
Old English
flanc — flank
Middle English
flanc
English, today
flank
From Late Middle English flanc, from Late Old English flanc (“flank”), from Old French flanc, of gem - origin, probably Frankish hlanca, from Proto-West Germanic hlanku (“bend, curve, hip, flank”), from Proto-Germanic hlankaz (“flexible, sleek, bendsome”), from Proto-Indo-European kleng- (“to bend”). Akin to Old High German hlanca (“loin”), Middle Low German lanke (“hip joint”) (German lenken (“to bend, turn, lead”)), Old English hlanc (“loose, slender, flaccid, lank”). More at lank.
Etymology from Wiktionary, CC BY-SA