pro ratapro ra·ta /prəʊ ˈrɑːtəproʊ ˈreɪtə/ adjectiveadj [only before a noun] a pro rata payment or share in something is calculated according to exactly how much of something is used, how much work is done etcThe residents here pay more than their pro rata share of taxes.
Fees for longer or shorter courses are calculated on a pro rata basis.
—pro rata adverbadvThe company directors are required to allot the shares to existing shareholders pro rata to the number of shares owned.