n. an extemporaneous speech or remark; "a witty impromptu must not sound premeditated"

n. a short musical passage that seems to have been made spontaneously without advance preparation

adv. "He spoke ad lib"

adj. in response to an unforeseen need; "a spur-of-the-moment party"

adj. with little or no preparation or forethought; "his ad-lib comments showed poor judgment"; "an extemporaneous piano recital"; "an extemporary lecture"; "an extempore skit"; "an impromptu speech"; "offhand excuses"; "trying to sound offhanded and reassuring"; "an off-the-cuff toast"; "a few unrehearsed comments"

adj. unprepared and unable to react quickly; "the new product caught their competitors flat-footed"

adj. made ready or fit or suitable beforehand; "a prepared statement"; "be prepared for emergencies"