Source : Webster's Revised Unabridged Dictionary (1913)

Septuagenary \Sep`tu*ag"e*na*ry\, a. [L. septuagenarius, fr.
   septuageny seventy each; akin to septuaginta seventy, septem
   seven. See {Seven}.]
   Consisting of seventy; also, seventy years old. -- n. A
   septuagenarian.