INFIRM Meaning of INFIRM in English ■ adjective1》 not physically strong, especially through age. 2》 archaic irresolute; weak.Derivatives~ly adverb OriginME: from L. ~us , from in- 'not' + firmus 'firm'. Concise Oxford English vocab. Сжатый оксфордский словарь английского языка. 2004