Lightning-fast
adj.energetic, capableplayful
What it means
Exceptionally quick in movement, response, or completion.
Reach for it when adding vivid emphasis when the speed is both unusual and relevant to the result
A lightning-fast alert gave every crew enough time to reach shelter.
Choose between these
7- everyday
plain language suits above-average speed
not when Quick is modest and does not convey an exceptional result.
- warm
speed is paired with smooth decisive action
not when Swift is strong but lacks lightning-fast's emphatic extremity.
- professional
high-speed
equipment operates in a defined fast mode
not when High-speed sounds technical and may still be slow relative to the event described.
- professional
rapid
high speed can be stated neutrally and measured
not when Rapid is less vivid and may describe a sustained rate rather than a near-instant response.
- formal
instantaneous
the event effectively takes no measurable time
not when Instantaneous is a literal technical claim and should not stand in for merely impressive speed.
- formal
action begins without avoidable delay
not when Promptness concerns timeliness, not the speed of execution after starting.
- literary
breakneck
dangerously extreme pace is part of the description
not when Breakneck warns of recklessness, whereas lightning-fast can praise safe response.
Said against
4- sluggish
- slow
- delayed
- leisurely
It naturally appears in
3- lightning-fast response
The lightning-fast response contained the kitchen fire to one room.
- lightning-fast reflexes
Lightning-fast reflexes helped the goalkeeper redirect the shot.
- lightning-fast speed
The camera's lightning-fast speed captured each wingbeat clearly.
Where this comes from
Cambridge lists lightning as an adjective meaning very fast and supplies lightning-fast in its usage evidence; Wiktionary had no standalone lightning-fast entry on the retrieval date.
Lightning-fast is not a headword in the dictionaries below. The sense was checked against their entries for lightning, and the definition and example here are written for Lightning-fast itself.
- cambridge, the entry for lightning, adjective (FAST), very fast sense opens in a new tab · retrieved 2026-07-26
The definition and the example on this page are written here. The dictionaries above ground which meaning is being described, not the wording.