DILIGENT Meaning of DILIGENT in English ■ adjective careful and conscientious in one's work or duties.Derivatives~ly adverb OriginME: via OFr. from L. diligens , ~- 'assiduous', from diligere 'love, take delight in'. Concise Oxford English vocab. Сжатый оксфордский словарь английского языка. 2004