Lewis & Short

octōgēni, ae, a

    (
  1. I. gen. plur. octogenūm, Front. Aquaed. 58), num. distr. adj. [octo], eighty each: data ex praedā militibus aeris octogeni bini, Liv. 10, 30.
  2. II. In gen., eighty: fetus, Plin. 9, 51, 75, § 165.