Added 9 October 2026 threesome /ˈθɹiː.səm/ noun Categories: Describing WordsSocietyRare Words noun ! Definition from WordNet 3.1, Princeton University. Pronunciation from Wiktionary, via Kaikki.org. More about threesome at Wordnik → Where our words come from → The cardinal number that is the sum of one and one and one. Three people considered as a unit. Related Words: triadtriotrinitytrinethreeternaryterniontiercetercettreyterzettotriplet Back to today's word