DEFAMATION Meaning of DEFAMATION in English def ‧ a ‧ ma ‧ tion /ˌdefəˈmeɪʃ ə n/ BrE AmE noun [uncountable] the act of defaming someone:He sued the newspaper for defamation of character. Longman Dictionary of Contemporary English. Longman - Словарь современного английского языка. 2012