happening /ˈhæpɪnɪŋ/adjective 2noun 2forms 4 adjective2 •(slang) Busy, lively; vibrant, dynamic; fashionable.“[…]San Francisco is not exactly the most happening place, you know.” — 2005 •(slang) Trendy, up-to-the-minute. noun2 •Something that happens.Three follow-up singles, all ecological or religious in theme, did chart in the lower reaches of the Hot 100. Thereafter, Ocean remained a Canadian happening. — 1990 •A spontaneous or improvised event, especially one that involves audience participation.And it was some kind of happening / Some kind of happening / Salvador Dali's garden party — 1989 formshappenings · more happening · happeningest · most happening