UNREHEARSED

extemporaneous, ad-lib, extemporary, extempore, impromptu, offhand, offhanded, off-the-cuff, unrehearsed

(adjective) 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”

Source: WordNet® 3.1

Etymology

Adjective

unrehearsed (comparative more unrehearsed, superlative most unrehearsed)

Not rehearsed

Source: Wiktionary