impromptu Definition

spontaneously, ad lib, unprepared, ad libitum, spur-of-the-moment, informal, improvised, spontaneous, makeshift, extemporaneous, adlib, hasty, temporary, unpredictable, interim, unforeseeable, unsolicited, provisional, ad-hoc, off-the-cuff, unrehearsed, extempore, unscheduled, unannounced, awkward, unplanned, improvisational, raucous, occasional, celebratory, uproarious, unscripted, boisterous, unexpected, perfunctory, riotous, unprompted, uneventful, serendipitous, quickie, desultory, comical, bizarre, offhanded, intimate, improvisate, hourlong, daylong, improvisatize, impassioned, mock, spirited, extemporal, brief, hour, exuberant, interminable, videotaped, unofficial, calisthenic, boozy, unsanctioned, rousing, obligatory, electrifying, acrobatic, rowdy, tearful, unamused, lighthearted, routine, unusual, weeklong, lively, imaginary, unanimated, odd, elaborate, mini, teary, jocular, offbeat, unruly, unorthodox, ersatz, unposed, offhand, abbreviated, exultant, backstage, testy, innocuous, amiable, ebullient, frenzied, undignified, monthlong, unforgettable, drunken, overenthusiastic,