Gib

"large, triangular foresail of a ship," 1660s, gibb, of uncertain origin. Perhaps related to gibbet on the notion of a sail "hanging" from a masthead [Barnhart, OED]; and compare gib "projecting arm of a crane." Or perhaps from the nautical verb jib, jibe "shift a sail or boom to the other side" (1690s), from Dutch gijben, gijpen "turn suddenly" (of sails), which is apparently related to gijk "boom or spar of a sailing ship."

An observant sailor watching a strange vessel approach at sea judges her character by the condition of the jibs; hence cut of (one's) jib "personal appearance" (1821). Related: Jib-boom (1748). The jib in jib-door "door flush with a wall" (1792) is of uncertain origin and probably is not the same word.

early 13c., "gallows," from Old French gibet "gallows; a bent stick, small stick with a cross" (13c.), diminutive of gibe "club; hoe," perhaps from Frankish *gibb "forked stick." "Originally synonymous with GALLOWS sb., but in later use signifying an upright post with projecting arm from which the bodies of criminals were hung in chains or irons after execution" [OED].