Late 17th century; earliest use found in Richard Baxter (1615–1691), ejected minister and religious writer. From classical Latin adprōmissor (also apprōmissor) person who promises or gives security for another (2nd cent. a.d.) from adprōmiss-, past participial stem of adprōmittere (also apprōmittere) to promise in addition (to another) (from ad- + prōmittere) + -or.