The term "walk-off" is a modern American English compound, originating in the mid-20th century from the sport of baseball. It is formed from the phrasal verb "to walk off," which literally means to depart by walking. In the specific sporting context, it humorously implies that the losing team can immediately "walk off" the field after the decisive play. The logic connects the literal action of leaving (walk off) with the figurative, abrupt conclusion of the game. This sports term has since broadened into general use to describe any sudden, conclusive ending.

Structure: walk (verb) + off (adverb/particle) walk: From Old English wealcan (to roll, toss) and wealcian (to roll up, curl), via Middle English walken (to move about). In this compound, it functions as a verb meaning to move on foot. off: From Old English of, a preposition/adverb of separation or movement away. In this compound, it functions as an adverbial particle indicating completion or finality.