Benign – English Flashcard for Benign with Synonyms Updated: June 24, 2019 by Dr. Mohammad Hossein Hariri AslBenignBenign (adj) /bɪˈnaɪn/(of a tumor) not malignant or fatal – not life-threatening – harmless – kind and gentle – caring:Some benign tumors might become malignant if not treated properly.