- knee (v.)
- early 13c., "to bend the knee, kneel," from Old English cneowian, from cneow (see knee (n.)). The meaning "to strike with the knee" is first recorded 1892. Related: Kneed; kneeing.
- knee (n.)
- "joint between the principal bones of the leg," Old English cneo, cneow "knee," from Proto-Germanic *knewam (source also of Old Norse kne, Old Saxon kneo, Old Frisian kni, Middle Dutch cnie, Dutch knie, Old High German kniu, German Knie, Gothic kniu), from PIE root *genu- (1) "knee; angle" (source also of Sanskrit janu, Avestan znum, Hittite genu "knee;" Greek gony "knee," gonia "corner, angle;" Latin genu "knee"). For pronunciation, see kn-.
To be across (someone's) knee in reference to spanking is from 1866. Knee-breeches is from 1827; knee-pants is from 1858. Knee-slapper "funny joke" is from 1955.