Definition of sponsor:

part of speech: noun

One who undertakes to answer for another; a godfather or godmother at baptism.

Usage examples:

• I have given you a great mark of confidence, for in lending you my influence I become, in some measure at least, your sponsor Emile Gaboriau in "Baron Trigault's Vengeance Volume 2 (of 2)".

• There are still governments that sponsor and harbor terrorists - but their number has declined. Various in "Complete State of the Union Addresses from 1790 to the Present".

• So you are going to play sponsor to my children once more! Eleanor Mercein Kelly in "Kildares of Storm".