Added 9 October 2026 three-eighths noun noun ! Definition from Wiktionary (CC BY-SA). More about three-eighths at Wordnik → Where our words come from → Three of eight equal parts (⅜, 0.375). Related Words: seven-eighthsfive-eighthsthree-quartersthree-fourthseighthone-thirdone-eighthfive-sixthsfour-fifthsthree-quarter Back to today's word