See also: irreductible French Etymology From ir- + réductible. Pronunciation IPA(key): /i.ʁe.dyk.tibl/ Audio:(file) Adjective irréductible (plural irréductibles) irreducible indomitable, implacable Derived terms irréductible Gaulois Further reading “irréductible”, in Trésor de la langue française informatisé [Digitized Treasury of the French Language], 2012.Wikiwand - on Seamless Wikipedia browsing. On steroids.