'third-to-last' originates from English, specifically the words 'third', 'to', and 'last', where 'third' meant 'the ordinal number three', 'to' served as a linking preposition, and 'last' meant 'the end or final'.

'third' comes from Old English 'þridda' (related to German 'dritte'), and 'last' comes from Old English 'lǣtst' / 'lǣsta' (from Proto-Germanic); the hyphenated compound 'third-to-last' arose in Modern English as a straightforward descriptive phrase meaning 'third from the end'.

Initially it was a literal combination describing position ('third toward the last'); over time it became a fixed adjectival expression synonymous with 'antepenultimate' meaning 'the third from the end'.