Spon"sor (?), n. [L., from spondere, sponsum, to engage one's self. See Spose.]
1.
One who binds himself to answer for another, and is responsible for his default; a surety.
2.
One who at the baptism of an infant professes the Christian faith in its name, and guarantees its religious education; a godfather or godmother.
© Webster 1913.