posthaste
As quickly as possible
Posthaste means with the greatest possible speed, as quickly as one can manage: The doctor was summoned posthaste.
The word sounds formal or old-fashioned, often appearing in official requests or period writing.
It derives from an instruction once written on urgent letters—"haste, post, haste"—commanding the courier to ride fast.
Without any pause
- straightawayWithout pause or hesitation
- forthwithWithout delay
- promptlyWithout hesitation or delay
- instantlyWithout any pause
urgently · hastily · swiftly · expeditiously · without delay · at once · right away · pronto
Without delay
- straightawayWithout pause or hesitation
- instantlyWithout any pause
- immediatelyWithout any pause
- promptlyWithout hesitation or delay
directly · pronto · at once · right away · without delay · instantaneous · unhesitating · sudden
Moving with speed
- rapidMoving with haste
- fastSpeedy, or skip eating
- quickMoving with speed
- fleetVehicles under unified command
speedy · brisk · express · lightning · meteoric · whirlwind · breakneck · headlong
Delivery person or service
- messengerOne who delivers communications
- relayStage-by-stage transmission
- express mailExpedited postal service
- special deliveryUrgent postal service
rush order · priority · expedite · fast-track · urgent message · communiqué · missive · same-day
immediately
Without any pause
- straightawayWithout pause or hesitation
- forthwithWithout delay
- promptlyWithout hesitation or delay
instantly · urgently · hastily · swiftly · expeditiously · without delay · at once · right away · pronto · stat
forthwith
Without delay
- straightawayWithout pause or hesitation
- instantlyWithout any pause
- immediatelyWithout any pause
promptly · directly · pronto · at once · right away · without delay · instantaneous · unhesitating · sudden · abrupt
swift
Moving with speed
fleet · speedy · brisk · express · lightning · meteoric · whirlwind · breakneck · headlong · precipitate
courier
Delivery person or service
- messengerOne who delivers communications
- relayStage-by-stage transmission
- express mailExpedited postal service
special delivery · rush order · priority · expedite · fast-track · urgent message · communiqué · missive · same-day · overnight
- speed adverbsquickly, fast, rapidly, swiftly, speedily
- Speed Expressionsin a flash, quick as a flash, in no time, lickety-split, lickety split
- Right Awaynow, instantly, immediately, promptly, forthwith
- suddennesssudden, suddenly, abrupt, abruptly, instant
posthasteslowly
At reduced speed
leisurely · sluggishly · unhurriedly · at a snail's pace · gradually
posthasteeventually
At a later time
tardily · belatedly · delinquently · in due time · in good time
hasty, haste, hasten, postal, post, hastiness, hastening, hastened, hastier