Wordnet 3.0
NOUN (1)
1. 
 (sports) the chief official (as in boxing or American football) who is expected to ensure fair play; 
[syn: referee, ref]
WordNet (r) 3.0 (2006):
ref
    n 1: (sports) the chief official (as in boxing or American
         football) who is expected to ensure fair play [syn:
         referee, ref]