forty-third I. \| ̷ ̷ ̷ ̷| ̷ ̷\adjective 1.: being number 43 in a countable series < the forty-third day > — see number table 2.: being one of 43 equal parts into which something is divisible < a forty-third share of the money > II. noun 1.: number 43 in a countable series 2.: the quotient of a unit divided by 43 : one of 43 equal parts of something < one forty-third of the total >