Added 9 October 2026 one-third noun Categories: Describing Words noun ! Definition from Wiktionary (CC BY-SA). More about one-third at Wordnik → Where our words come from → One of three equals parts (1/3, ⅓, 0.333…). Related Words: tiercethirdone-quartertwo-thirdsthird-partythirdsnon-memberthree-foldtwothirdsthree-quartersthirdingthirty-third Back to today's word