Added 10 October 2026 summation /sʌˈmeɪʃən/ noun Categories: LanguageActionsUncommon Words noun ! Definition from Wiktionary (CC BY-SA). Pronunciation from Wiktionary, via Kaikki.org. More about summation at Wordnik → Where our words come from → Summarization; summary; summing up. Summing; summing up; adding (adding up) of a series of items. Related Words: rundownadditionplussummarisesummarizationsummarizewrap-uprecapitulationabstractaddendumsumming Back to today's word