Added 10 October 2026 blastocyst /ˈblæstəsɪst/ noun Categories: AnimalsRare Words noun ! Definition from Wiktionary (CC BY-SA). Pronunciation from Wiktionary, via Kaikki.org. More about blastocyst at Wordnik → Where our words come from → The mammalian blastula. Related Words: unilaminarbastocystblastulablastulationblastulecoeloblastulablastocytearchiblastulablastospheremorulablastomerblastocoel Back to today's word