one who or that which acts or does: improvisator
Origin of -atorMiddle English -atour ; from Old French ; from Classical Latin -ator: see -ate and amp; -or
One that acts in a specified manner: radiator.
Origin of -atorLatin -ator : -a-, stem vowel of verbs in -are + -tor, agent n. suff. (later reanalyzed as -atus, -ate + -or, -or).