Source : Webster's Revised Unabridged Dictionary (1913)

Sponsor \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 professore the
      christian faith in its name, and guarantees its religious
      education; a godfather or godmother.

Source : WordNet®

sponsor
     n 1: someone who supports or champions something [syn: {patron},
          {supporter}]
     2: an advocate who presents a person (as for an award or a
        degree or an introduction etc.) [syn: {presenter}]

sponsor
     v 1: assume sponsorship of [syn: {patronize}, {patronise}]
     2: assume responsibility for or leadership of; "The senator
        announced that he would sponsor the health care plan"
     3: do one's shopping at; do business with; be a customer or
        client of [syn: {patronize}, {patronise}, {shop}, {shop at},
         {buy at}, {frequent}] [ant: {boycott}, {boycott}]