sponsor

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun One who assumes responsibility for another person or a group during a period of instruction, apprenticeship, or probation.
• noun One who vouches for the suitability of a candidate for admission, as to an organization.
• noun A legislator who proposes and urges adoption of a bill.
• noun Christianity One who presents a candidate for baptism or confirmation; a godparent.
• noun One that finances a project, event, or organization directed by another person or group, such as a business enterprise that pays for radio or television programming in return for advertising time.
• transitive verb To act as a sponsor for.

from The Century Dictionary.

• noun A surety; one who binds himself to answer for another, and is responsible for his default; specifically, one who is surety for an infant at baptism, professing the Christian faith in its name, and guaranteeing its religious education; a godfather or godmother. The custom of having sponsors in baptism is as old as the second century. See godfather.
• noun In entomology, a genus of coleopterous insects.

from the GNU version of the Collaborative International Dictionary of English.

• noun One who binds himself to answer for another, and is responsible for his default; a surety.
• noun One who at the baptism of an infant professes the Christian faith in its name, and guarantees its religious education; a godfather or godmother.
• noun A person who vouches for another as fit for some post or task.
• noun A person or group that assumes financial responsibility for some activity, and may or may not participate in its organization and execution.
• noun A person or organization, usually a commercial organization, which pays the cost of an activity, such as a radio or television broadcast, and in return is given the right to advertise itself or its products as part of the activity.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A person or organisation with some sort of responsibility for another person or organisation, especially where the responsibility has a religious, legal, or financial aspect.
• noun One that pays all or part of the cost of an event, a publication, or a media program, usually in exchange for advertising time.
• noun A senior member of a twelve step or similar program assigned to a guide a new initiate and form a partnership with him
• verb transitive To be a sponsor for.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun an advocate who presents a person (as for an award or a degree or an introduction etc.)
• verb assume responsibility for or leadership of
• verb assume sponsorship of
• noun someone who supports or champions something
• verb do one's shopping at; do business with; be a customer or client of