/ ˌprəʊ ˈrɑːtə; NAmE ˌproʊ/ adjective
(from Latin , formal ) ( of a payment or share of sth ) calculated according to how much of sth has been used, the amount of work done, etc.
SYN proportionate :
If costs go up, there will be a pro rata increase in prices.
► pro rata adverb :
Prices will increase pro rata.
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WORD ORIGIN
late 16th cent.: Latin , literally according to the rate .