'Strike zone' definitions:

Definition of 'strike zone'

From: WordNet
noun
(baseball) the area over home plate between a batter's knees and shoulders through which a pitch must pass in order to be called a strike

Definition of 'Strike zone'

From: GCIDE
  • Strike zone \Strike" zone\, n. (Baseball) the area above home plate where, if a pitched ball passes through and is not hit by the batter, the pitch counts as a strike. Specifically, it is directly above home plate and at a height from the knees to the shoulders of the batter. [PJC]