[proh-reyt, proh-reyt]
verb (used with object), pro·rat·ed, pro·rat·ing.
  1. to divide, distribute, or calculate proportionately.

Origin of prorate

1855–60, Americanism; partial translation of pro rata
Related formspro·rat·a·ble, adjectivepro·ra·tion, noun Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for proration


  1. mainly US and Canadian to divide, assess, or distribute (something) proportionately
Derived Formsproratable, adjectiveproration, noun

Word Origin for prorate

C19: from pro rata
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for proration

1893, noun of action from prorate (v.).



also pro-rate, "divide proportionally," 1860, American English, verb derived from Latin pro rata (parte) (see pro rata). Related: Prorated; prorating.

Online Etymology Dictionary, © 2010 Douglas Harper

proration in Culture


To divide or distribute a sum of money proportionately. For example, if one owned an automobile for only three months, an insurance company would prorate the annual premium by charging only one-quarter of it.

The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.