From Google toolbar search (define: Impromptu) an extemporaneous speech or remark; "a witty impromptu must not sound premeditated" ad lib: Without advance preparation; "he spoke ad lib" ad-lib: 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 ...
wordnet.princeton.edu/perl/webwn
wordnet.princeton.edu/perl/webwn