1650s, from Late Latin sponsor "sponsor in baptism," in Latin "a surety, guarantee," from sponsus, past participle of spondere "give assurance, promise solemnly" (see spondee). Sense of "person who pays for a radio (or, after 1947, TV) program" is first recorded 1931. The verb is attested from 1884, "to favor or support;" commercial broadcasting sense is from 1931.