The compound "third-generation" is a modern English formation built from two foundational elements. "Third" descends from the Proto-Indo-European root trei- (three), which evolved through Proto-Germanic into the Old English ordinal number. "Generation" traces back to the Latin genus (birth, race, kind), from the PIE root gene- (to give birth, beget). The logic of the compound is straightforwardly numerical and classificatory: it literally denotes "the third stage of begetting or production." This literal sense evolved from describing familial lineage (the third group of descendants) to its prevalent modern abstract meaning in technology and sociology, categorizing the third major stage in the development of a system, product, or immigrant community.

Structure: third (number) + generation (stage of descent/development) - third: From Old English þridda, from Proto-Germanic þridjô, meaning "coming next after the second." Functions as a numerical determiner. - generation: From Latin generātiōn- (stem of generātiō), from generāre meaning "to beget." Functions as a noun-forming suffix indicating a stage or group.