- a gesture of greeting, good-fellowship, or triumph in which one person slaps the upraised palm of the hand against that of another.
- a gesture of greeting or congratulation in which two people slap raised right palms together
- to greet or congratulate (a person) in this way
originally U.S. basketball slang, 1980 as a noun, 1981 as a verb, though the greeting itself seems to be older (e.g. Dick Shawn in “The Producers,” 1968). In reference to the five fingers of the hand.