calypso, a type of folk song primarily from Trinidad though sung elsewhere in the southern and eastern Caribbean islands. The subject of a calypso text, usually witty and satiric, is a local and topical event of political and social import, and the tone is one of allusion, mockery, and double entendre. The calypso tradition, popularized abroad in the late 1950s, dates to the early 19th century and was originally called caïso or cariso. During the carnival season before Lent, groups of slaves led by popular singers, or shatwell, wandered through the streets singing and improvising veiled lyrics directed toward unpopular