The term is a modern American English compound noun, directly combining the cardinal number "three" with the plural noun "strikes." Its primary legal sense is a metaphorical extension from baseball terminology, where a "strike" is a penalty against the batter, and three strikes result in an out. This sporting metaphor was adopted into U.S. criminal justice discourse in the 1990s to describe laws mandating life imprisonment after a third serious felony conviction, framing repeated offenses as successive "strikes." The logic hinges on the simple, universally understood counting system of "three" and the consequential finality associated with the third "strike."

Structure: three (number) + strikes (blows/offenses) - three: From Old English þrīe, þrēo, from Proto-Germanic þrīz, from Proto-Indo-European tréyes. Functions as a numerical quantifier. - strikes: From Old English strīcan (to stroke, go, proceed), from Proto-Germanic strīkana. In this compound, it functions as a noun meaning 'blows' or, by extension, 'recorded offenses'.