seventy-eighth I. \| ̷ ̷ ̷ ̷ ̷ ̷| ̷ ̷\adjective 1.: being number 78 in a countable series < the seventy-eighth day > — see number table 2.: being one of 78 equal parts into which something is divisible < a seventy-eighth share of the money > II. noun 1.: number 78 in a countable series 2.: the quotient of a unit divided by 78 : one of 78 equal parts of something < one seventy-eighth of the total >