(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 WordNet 3.0 & Open English WordNet

A fair catch is a feature of American football and several other codes of football, in which a player attempting to catch a ball kicked by the opposing team – either on a kickoff or punt – is entitled to catch the ball without interference from any member of the kicking team. Wikipedia

A uncontested catch on a kicking play, after the receiver waves his hand to indicate that he will not run with the ball, assuring that he will not be tackled on catching it. Wiktionary