A protective garment worn on a knee to protect it from injury, for example due to a blow or a fall.

The action of striking one's own knee with the hand, associated with hearty laughter.

Unthinking, not carefully considered, (nearly) automatic, spontaneous, easily predictable.

(cricket) the thick part of a batsman's pads that protects the knee

(Britain, informal) A party.

(idiomatic, colloquial) Something or someone excellent, surpassingly wonderful, or cool. / Used other than figuratively or idiomatically: see bee, -'s, knee. Corbiculae.

A sudden reflexive movement of the leg below the knee, as a reaction to a tap to the tendon just below the patella (kneecap).

(idiomatic) A joke, especially one which strikes the listener or reader as particularly humorous.

Reaching up to the knees. / Submerged to the knees. / (figuratively, by extension) Deeply involved in something, or preoccupied with something.

Reaching to the height of a person's knees.