We don't have synonyms for extemporises yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are extemporize, extemporise and extemporiser.
(v) :
(intransitive) To do something, particularly to perform or speak, without prior planning or thought; to act in an impromptu manner; to improvise.
(v) :
(transitive, music) To compose extemporaneously or improvise.
(v) :
(intransitive) To do something in a makeshift way.
(v) :
(intransitive) To do something, particularly to perform or speak, without prior planning or thought; to act in an impromptu manner; to improvise.
(v) :
(transitive, music) To compose extemporaneously or improvise.
(v) :
(intransitive) To do something in a makeshift way.