extemporize
Concise Oxford English Dictionary © 2008 Oxford University Press:
extemporize /ɪkˈstempərʌɪz/ (or extemporise /ɪkˈstɛmpərʌɪz, ɛk-/)
▶verb compose or perform without preparation; improvise.
– derivatives
extemporization noun.
extemporization noun.
'extemporize' also found in these Oxford entries:

