fifty-fifth I. \| ̷ ̷ ̷ ̷| ̷ ̷\adjective 1.: being number 55 in a countable series < the fifty-fifth day > — see number table 2.: being one of 55 equal parts into which something is divisible < a fifty-fifth share of the money > II. noun 1.: number 55 in a countable series 2.: the quotient of a unit divided by 55 : one of 55 equal parts of something < one fifty-fifth of the total >