a person who vouches or is responsible for a person or thing.

a person, firm, organization, etc., that finances and buys the time to broadcast a radio or television program so as to advertise a product, a political party, etc.

a person who makes a pledge or promise on behalf of another.

a person who answers for an infant at baptism, making the required professions and assuming responsibility for the child's religious upbringing; godfather or godmother.

to act as sponsor for; promise, vouch, or answer for.

noun

aegis , auspice , backing , patronization , advocacy , aid , angel , auspices , benefactor , egis , guardianship , patron , patronage , protection , protectorship , sponsor , support , tutelage