MADDENING Meaning of MADDENING in English mad ‧ den ‧ ing /ˈmæd ə nɪŋ/ BrE AmE adjective very annoying SYN infuriating :maddening delays —maddeningly adverb :He moved carefully and maddeningly slowly. Longman Dictionary of Contemporary English. Longman - Словарь современного английского языка. 2012