'Fair catch' definitions:

Definition of 'fair catch'

(from WordNet)
noun
(American football) a catch of a punt on the fly by a defensive player who has signalled that he will not run and so should not be tackled

Definition of 'Fair catch'

From: GCIDE
  • Fair catch \Fair catch\ (Football) A catch made by a player on side who makes a prescribed signal that he will not attempt to advance the ball when caught. He must not then be interfered with. [Webster 1913 Suppl.]