Origin and history of *el-

"bend of the arm," c. 1200, elbowe, from a contraction of Old English elnboga "elbow," from Proto-Germanic *elino-bugon, literally "bend of the forearm" (source also of Middle Dutch ellenboghe, Dutch elleboog, Old High German elinbogo, German Ellenboge, Old Norse ölnbogi).

First element is from PIE *elina "arm," from root *el- "elbow, forearm." Second element is from Proto-Germanic *bugon-, from PIE root *bheug- "to bend." To be out at elbows (1620s) was literally to have holes in one's coat. Phrase elbow grease "hard rubbing" is attested from 1670s, from jocular sense of "the best substance for polishing furniture." Elbow-room "room to extend one's elbows," hence, "ample room for activity," is attested from 1530s.

unit of measure, Old English eln, originally "forearm, length of the arm" (as a measure, anywhere from a foot and a half to two feet), from PIE root *el- "elbow, forearm." The exact distance varied, in part depending on whose arm was used as the base and whether it was measured from the shoulder to the fingertip or the wrist: the Scottish ell was 37.2 inches, the Flemish 27 inches. Latin ulna also was a unit of linear measure, and compare cubit. The modern English unit of 45 inches seems to have been set in Tudor times.

Whereas shee tooke an inche of liberty before, tooke an ell afterwardes [Humfrey Gifford, "A Posie of Gilloflowers," 1580].