effulgent UK /ɪˈfʌldʒ(ə)nt/US /ɪˈfʌld͡ʒənt/ adjective1 •(literary) Radiant, resplendent, shining.Margaret, aged six, entered her kindergarten after many days' absence, with so effulgent a face as must kindle curiosity in the dullest. — 1904 formsmore effulgent · most effulgent