means A style of music born in the African-American communities of the American South, built on improvisation, swing, syncopation, and blue notes — or, more loosely, any lively embellishment or unnecessary extra stuff ('and all that jazz').

from American slang that surfaced in the early 20th century, first spotted in print around baseball before it stuck to music. Its deeper roots are genuinely murky and much-argued: it may trace to a now-lost slang word meaning energy, pep, or vigor — and some link it to Creole or West African terms, though none of these is proven. The word lived a slangy, sometimes risqué life before it settled into the name of a glorious art form, which is why nobody can pin down exactly where it came from — a fittingly improvised origin story.