post haste
Preserved but no longer current.
With great speed or expedition. The allusion is to the old coaching days, when travelling by relays of horses, or with horses placed on the road to expedite the journey, was the rule in cases of urgency.
Era: ca. 1898 (Victorian)
Sources & notes
Reproduced from Brewer’s Dictionary of Phrase and Fable (1898 edition, public domain; archive.org, retrieved 2026-07-31; OCR text, minor errors possible). Reflects the scholarship and attitudes of its era.
Common questions
What does “post haste” mean?
With great speed or expedition. The allusion is to the old coaching days, when travelling by relays of horses, or with horses placed on the road to expedite the journey, was the rule in cases of urgency.
Is “post haste” formal or informal?
No register label has been reviewed yet — treat it as neutral and check the usage notes above.