A similar question has been asked.

However, is it possible to give (general) differences in usage of fast, quickly, speedy and rapidly?

And with respect to the top answer: Are quick and fast absolutely interchangeable?

  • 3
    No two English words are absolutely interchangeable. – Oldcat Apr 9 '14 at 19:42
  • 2
    Pitchers throw fast balls, not quick balls. You dance the quickstep, not the faststep. – Peter Shor Apr 9 '14 at 21:11
  • Nobody ever says 'The fast and the dead' – Oldcat Apr 9 '14 at 21:12
  • There is also the matter of the adverbial '-ly' suffix, which American English tends to avoid. 'I ran quick' vs 'I ran quickly'. – toandfro Apr 9 '14 at 21:40
  • Besides the association with 'life' or 'living', quick generally refers to acceleration. Consider two hypothetical cars: a car that could go from 0-60mph in one second but had a top speed of only 65mph would be quick but not fast; a car whose top speed was 500mph but took ages to accelerate to that speed would be fast but not quick. – MT_Head Sep 2 '14 at 18:12

I do not think it is strictly possible to give guidelines to usage that are anything other than pedantic. I do, however, think that etymology provides some helpful clues to the more natural contexts of usage.

Quick is related to life and living things such that "quick as a rabbit" seems natural.

Fast has its relationship to strength and force that makes "fast cars" and "run a fast race" seem like a good fit.

Speed is related to success and goals giving "speed limit" and "speedy delivery" their purposeful ring.

Rapid has a hunger to it that makes it well suited to phrases like "consume at a rapid rate" or "rapidly overtaking."

Mixing these up produces some odd results: "Rapid rabbits" are comprehensible but more predatory that we are used to rabbits being. "Quickness limits" Nonsense. "Quick delivery?" Something else entirely. A baby has been born. Further evidence that "quick" wants to talk about life.

There are certainly no rules, just clues buried in the historical antecedents of the modern words. I would say try "quick" first for natural systems and living things and use "fast" as the go-to for machines, forces and acts of power. Rapid has a dark side. Speed is ambitious.

  • Speed: Old High German spuon to succeed Quick: Gothic qius alive Fast: Middle High German vaste firmly Rapid: Latid rapere to seize – Aaron K Apr 9 '14 at 21:21
  • Concise explanation, vivid examples. – Denis Gorbachev Dec 19 '14 at 15:52
  • Quick delivery can be a pizza just as much as a baby. And probably more often. – Steven Littman Feb 20 '16 at 20:11
  • NGram disagrees. Writers in the modern era are more likely to use "quick delivery" for the birth of a child. (quick delivery+baby),(quick delivery + pizza). However adjusting for the relative frequency of the words pizza and baby: ((quick delivery+baby)/baby),((quick delivery + pizza)/pizza) does reveal that rarely when talking about a baby is quick delivery the key point. Pizza however has less going on and quick delivery of a pizza is one of its most salient features. – Aaron K May 19 '18 at 19:25
  • Would you say "the value decreases rapidly/quickly/other..."? – skan Dec 27 '18 at 19:58

protected by tchrist Aug 4 '14 at 2:06

Thank you for your interest in this question. Because it has attracted low-quality or spam answers that had to be removed, posting an answer now requires 10 reputation on this site (the association bonus does not count).

Would you like to answer one of these unanswered questions instead?