QUINQUAGENARIAN Meaning of QUINQUAGENARIAN in English [ ˌkwɪŋkwədʒɪ'nɛ:rɪən ]■ noun a person between 50 and 59 years old.OriginC19: from L. quinquagenarius (based on quinquaginti 'fifty') + -an . Concise Oxford English vocab. Сжатый оксфордский словарь английского языка. 2004