O / octōgēsĭmus
adjective

octōgēsĭmus

fem. octōgēsĭma · neut. octōgēsĭmum
the eightieth
num. ord. adj. [octoginta], the eightieth: quartum annum ago et octogesimum, Cic. Sen. 10, 32; 2, 4: solstitia, Juv. 4, 92.