QUADRAGENARIAN Meaning of QUADRAGENARIAN in English [ ˌkwɒdrədʒɪ'nɛ:rɪən ]■ noun a person who is between 40 and 49 years old.OriginC19: from late L. quadragenarius (based on L. quadraginta 'forty') + -an . Concise Oxford English vocab. Сжатый оксфордский словарь английского языка. 2004