eighty-ninth I. \| ̷ ̷ ̷ ̷| ̷ ̷\adjective 1.: being number 89 in a countable series < the eighty-ninth day > — see number table 2.: being one of 89 equal parts into which something is divisible < an eighty-ninth share of the money > II. noun 1.: number 89 in a countable series 2.: the quotient of a unit divided by 89 : one of 89 equal parts of something < one eighty-ninth of the total >