sep ‧ tu ‧ a ‧ ge ‧ nar ‧ i ‧ an /ˌseptʃuədʒəˈneəriən, ˌseptʃuədʒɪˈneəriən $ -ˈner-/ BrE AmE noun [countable]
[ Date: 1700-1800 ; Language: Latin ; Origin: septuagenarius 'containing seventy' , from septuaginta 'seventy' ]
someone who is between 70 and 79 years old