Webster’s Revised Unabridged Dictionary · 1913
Prorate
Pro·rate′ (·rāt′), v. t. [imp. & p. p. Prorated; p. pr. & vb. n. Prorating.] [From L. pro rata (sc. parte) according to a certain part, in proportion.] To divide or distribute proportionally; to assess pro rata. [U.S.]