[ pohst-heyst ]
See synonyms for posthaste on
  1. with the greatest possible speed or promptness: to come to a friend's aid posthaste.

  1. Archaic. great haste.

Origin of posthaste

First recorded in 1530–40; post3 + haste Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use posthaste in a sentence

  • The man says, that his Lordship was so bad when he came away, that the family began to talk of sending for me in post haste.

    Clarissa, Volume 6 (of 9) | Samuel Richardson

British Dictionary definitions for posthaste


/ (ˈpəʊstˈheɪst) /

  1. with great haste; as fast as possible

  1. archaic great haste

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

Cultural definitions for posthaste


[ (pohst-hayst) ]

Immediately, with great speed: “Get the flood warning to the media posthaste.”

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.