1820–30, Americanism; back formation from enthusiasm

The verb enthuse is a 19th-century back formation from the noun enthusiasm. Originally an Americanism, enthuse is now standard and well established in the speech and all but the most formal writing of educated persons, in both Britain and the United States. It is used as a transitive verb meaning “to cause to become enthusiastic” ( The liveliness of the dance enthused the audience ) and as an intransitive verb meaning “to show enthusiasm” ( She enthused warmly over his performance ). Despite its long history and frequent occurrence, however, enthuse is still strongly disapproved of by many.