Synonyms of impromptu in English:

impromptu


See definition of impromptu

adjective

1‘he gave an impromptu lecture’

SYNONYMS
unrehearsed, unprepared, unscripted, extempore, extemporized, improvised, improvisational, improvisatory, improvisatorial, spontaneous, unstudied, unpremeditated, unarranged, unplanned, on the spot, snap, ad lib
ad hoc, thrown together, cobbled together, rough and ready
ad libitum
informal off-the-cuff, spur-of-the-moment
rare extemporaneous
ANTONYMS

prepared, rehearsed


adverb

1‘they played the song impromptu’

SYNONYMS
extempore, spontaneously, without preparation, without rehearsal, on the spur of the moment, offhand, ad lib
ad libitum
informal off the cuff, off the top of one's head
rare extemporaneously