The term is a modern compound specific to baseball statistics, formed transparently from common English elements. The numeral "three" quantifies the extremely low number of successful strikes ("hits") a pitcher allows. The agent suffix "-er" is attached to the verbal noun "hit," but in this context, it refers not to a person but to the game event itself characterized by that number of hits. Thus, the literal construction "a three-hitter" logically tells the story of a game where the pitcher was so dominant that only three batters successfully struck the ball for a hit.

Structure: three (number) + hit (strike) + er (agent suffix) - three: From Old English þrīe, of Proto-Germanic origin; functions as a numerical quantifier. - hit: From Old English hittan (to meet with, strike), of Proto-Germanic origin; functions as the core verb denoting the action of striking the ball. - er: From Old English -ere, an agent-noun suffix of Proto-Germanic origin; functions to denote a person or thing associated with the action.