extemporaneous
Concise Oxford English Dictionary © 2008 Oxford University Press:
extemporaneous /ɪkˌstɛmpəˈreɪnɪəs, ɛk-/
▶adjective another term for extemporary.
– derivatives
extemporaneously adverb,
extemporaneousness noun.
extemporaneously adverb,
extemporaneousness noun.
'extemporaneous' also found in these Oxford entries:

