humor : (a) that quality which appeals to a sense of the ludicrous or absurdly incongruous (b) the mental faculty of discovering, expressing, or appreciating the ludicrous or absurdly incongruous (c) something that is or is designed to be comical or amusing — Merriam-Webster See also OneLook
Humor is the tendency of particular cognitive experiences to provoke laughter and provide amusement. The term derives from the humoral medicine of the ancient Greeks, which taught that the balance of fluids in the human body, known as humours (Latin: humor, “body fluid”), controlled human health and emotion. People of all ages and cultures respond to humour. Most people are able to experience humour — be amused, smile or laugh at something funny — and thus are considered to have a sense of humour. The hypothetical person lacking a sense of humour would likely find the behaviour inducing it to be inexplicable, strange, or even irrational. Though ultimately decided by personal taste, the extent to which a person finds something humorous depends on a host of variables, including geographical location, culture, maturity, level of education, intelligence and context. — Wikipedia
Joke is a display of humour in which words are used within a specific and well-defined narrative structure to make people laugh and is usually not meant to be interpreted literally. It usually takes the form of a story, often with dialogue, and ends in a punch line, whereby the humorous element of the story is revealed; this can be done using a pun or other type of word play, irony or sarcasm, logical incompatibility, hyperbole, or other means. — Wikipedia
Here are links to pages about closely related subjects.
Entertainment Humor, Toy, Hobby, Competition (Game, Sport), Spectacle
Arts Performing, Visual (Architecture), Culinary, Language (Poem), Music, Dance
Belief Hypothesis, Forecast, Rumor, Superstition, Folklore, Faith