Synonyms for Post-haste:

• adj.

  •fast (adjective)
  • chop-chop,
  • racing,
  • flying,
  • brisk,
  • flashing,
  • like all get out,
  • on the double,
  • like a bat out of hell,
  • active,
  • like crazy,
  • winged,
  • presto,
  • like mad,
  • hairtrigger,
  • agile,
  • hurried,
  • hypersonic,
  • in a jiffy,
  • snappy,
  • electric,
  • PDQ,
  • velocious,
  • BLUE STREAK,
  • in nothing flat,
  • accelerated,
  • Lickety Split,
  • ready,
  • Expeditive,
  • supersonic,
  • screamin',
  • nimble,
  • speedball,
  • hot,
  • double-time,
  • fleeting,
  • dashing,
  • Posthaste.
  •quick (adjective)
  • brief,
  • mercurial,
  • immediate,
  • alert,
  • spry,
  • energetic,
  • instantaneous,
  • impatient,
  • sudden,
  • perfunctory,
  • going,
  • abrupt,
  • prompt,
  • spirited,
  • cursory,
  • lively,
  • keen,
  • express,
  • sprightly,
  • asap,
  • impetuous,
  • animated,
  • curt.

• adv.

  •all (adverb)
  • post-haste.
  •fast (adverb)
  • like greased lightning,
  • apace,
  • expeditiously,
  • like a shot,
  • in short order,
  • in haste,
  • like wildfire,
  • soon,
  • like a flash,
  • hurriedly,
  • in a flash.
  •hastily (adverb)
  • carelessly,
  • too quickly,
  • on spur of the moment,
  • impulsively,
  • rashly,
  • precipitately,
  • thoughtlessly,
  • fast,
  • suddenly,
  • Subito,
  • nimbly,
  • prematurely,
  • Unpremeditatedly,
  • agilely,
  • recklessly,
  • impetuously,
  • heedlessly.
  •pell-mell (adverb)
  • helter-skelter,
  • indiscreetly,
  • precipitiously,
  • Incontinently,
  • foolishly.
  •promptly (adverb)
  • on time,
  • punctually,
  • unhesitatingly,
  • sharp,
  • now.
  •soon (adverb)
  • coming down the pike,
  • short,
  • in a little while,
  • betimes,
  • forthwith,
  • shortly,
  • in due time,
  • ANON,
  • early,
  • in time,
  • before long,
  • by and by,
  • in a short time,
  • presently,
  • any minute now,
  • ere long,
  • in a minute,
  • in a second.

• Other synonyms:

  •Other relevant words:
  • immediately,
  • like the wind,
  • once,
  • in a wink,
  • right away,
  • on the run,
  • at full tilt,
  • like lightning,
  • briskly,
  • instantly,
  • straight away,
  • at top speed,
  • at the double,
  • at maximum speed,
  • at full speed,
  • in a trice,
  • without delay,
  • p.d.q.,
  • flat,
  • at breakneck speed,
  • instantaneously.

Antonyms for Post-haste:

• adj.

  • fast
    plodding, unhurried, tardy.
  • quick
    sluggish, lazy.

• a. & adv.

  • posthaste
    eventually, slowly, slow.

• adv.

  • hastily
    delayed.
  • pell-mell
    cautiously, carefully.
  • promptly
    negligently, late.
  • rapidly
    leisurely.
  • soon
    never, far, later, distant.
  • swiftly/swift
    sluggishly.