Answer: What is the difference between "fast" and "quick"?

[theemdash]

with examples from the Roadrunner, Buffy the Vampire Slayer, Stargate: SG-1 and Harry Potter

roadrunner1896 asks: What is the difference between "fast" and "quick"?

"Fast" and "quick" can be adjectives, adverbs, or nouns. In struggling to come up with examples, I think the words are most interchangeable when used as adjectives generally describing speed, but are less interchangeable (or not at all interchangeable) when used in adjectival phrases. (When the words are used as nouns they have completely different meanings and as an adverb "quick" should be "quickly.")

Adjectives
In their adjective forms, "fast" and "quick" are fairly similar as evidenced by their definitions:

fast adj. moving or able to move, operate, function, or take effect quickly; quick; swift; rapid

quick adj. done, proceeding, or occurring with promptness or rapidity, as an action, process

You can say:
The Roadrunner is fast.
The Roadrunner is quick.

Closing the Hellmouth (one of a zillion times) required fast thinking.
Closing the Hellmouth (one of a zillion times) required quick thinking.

However, reading these sentence pairs, one sounds "more right" than the other, doesn't it? Taking the literal meaning, all four examples are correct, however I'd be more likely to say "The Roadrunner is fast" and "Closing the Hellmouth (one of a zillion times) required quick thinking." Just a personal preference or is there something more there?

Adjectival Phrases
While still being used as adjectives, "fast" and "quick" can have very specific meanings when modifying certain words.

fast adj. characterized by unrestrained conduct or lack of moral conventions, esp. in sexual relations; wanton; loose
ex. Vala is fast, as evidenced by her penchant for leather.
fast adj. firm in adherence; loyal; devoted
ex. Harry and Ron were fast friends which is why Ron always wanted to come back.

quick adj. easily provoked or excited
ex. Touch Daniel's artifacts and you'll find out that he can be quick tempered.
quick adj. prompt to understand, learn, etc.; of ready intelligence:
ex. Hermione is a quick student, the cleverest witch of her age.

"Fast" and "quick" aren't interchangeable in those examples or for those meanings. (Though I think some people will mistakenly use "quick" in that first example of "Vala is fast".) And before anyone points it out: "a quick student" is different from "a fast learner." "A quick student" is implying something about the student herself, whereas "a fast learner" describes the speed at which one learns.

Etymology
My fellow grammarian superhero_specs did further research on the etymologies of the words and came up with the following information:

Interestingly, it appears that fast "moving or capable of moving at a high speed" comes from the same root as fast "firmly fixed or attached" by way of "firmly, securely" -> "close, immediate" -> "immediately" -> "quickly".

Likewise, quick "moving fast or doing something in a short time" and quick "the soft, tender flesh below the growing part of a fingernail or toenail," both come from the same word meaning "alive, animated, alert."

Similar etymological information can be found at etymonline.com: fast and quick

Knowing those roots, it seems to imply that "fast" should primarily be used in conjunction with an action that occurs in a short period of time whereas "quick" has to do with the completion of an action in a short time (a "fixed" state (or speed) as opposed to an "animated" state).

I think you can see that in (some of) the examples used for the adjectival phrases:

Harry and Ron were fast friends which is why Ron always wanted to come back.
Harry and Ron continue being friends, a "fixed" condition.

Touch Daniel's artifacts and you'll find out that he can be quick tempered.
The action here of Daniel having a quick temper is instantaneous, an "animation" of anger.

It's interesting to look at those first examples—the ones in which fast and quick were interchangeable—with this etymological evidence in mind. What I thought was merely a personal preference may actually be based in usage. "The Roadrunner is fast" implies a continued state (the Roadrunner is always fast), whereas "Closing the Hellmouth (one of a zillion times) required quick thinking" is describing a single event.

Summary: So, roadrunner1896, to answer your question, the difference between "fast" and "quick" (when used as adjectives) isn't articulated in any solid-and-steadfast rules. It depends on usage and knowing that while the words are synonyms, they can't arbitrarily replace each other. Looking at what is being described and whether or not it is in a "fixed" or "animated" state may be the best way to handle this particular facet of the English language.

All definitions from dictionary.com

Comments

[roadrunner1896.livejournal.com]

I know. :D

*hugs back*

I asked the question in private. I didn't know it would end up in a public community. But I was really interested since I had to think about it for a work email way too long.

And learning stuff is always good. Glad other people can get something out of it as well.

[theemdash]

I asked you about using it first. (Or rather I think I told you I was going to do it because I thought others would benefit. The point is that you agreed.)

Honestly, I got a lot out of answering the question because I had to really consider how the words are used in context and examine if that context is ever different. It really is a challenging question.

[roadrunner1896.livejournal.com]

More the second one. And what was I supposed to do when you said you will use it? Tell you not to? Hire a lawyer? Na. I also like that others can benefit from it as well. And this community is an awesome idea. I love fandom and learning stuff. So learning stuff through fandom is twice as great. :D

[theemdash]

I'm very happy that my whole idea finally grew into this. I think this is actually going to be something that can be maintained and blossom into a beautiful thing.

[roadrunner1896.livejournal.com]

Just like a child. So if you hadn't already had the idea for this, I could have gotten you pregnant in a less awkward way. :D

Okay, that sentence sounds wrong. Correct me!

[theemdash]

Actually, it's not wrong, just clumsy. So, if you didn't already have the idea for this, I could have gotten you pregnant in a less awkward way. That makes it less awkward.

[roadrunner1896.livejournal.com]

Well, it sounded weird, but I am glad that it was at least not wrong.

I like how getting you pregnant in a less awkward way makes it less awkward. ;)

*snuggles*

[theemdash]

Well, it would still awkward. But on an awkward scale, maybe only a 7 instead of a 9.

[roadrunner1896.livejournal.com]

Well, I think we can handle a 7 awkward with a little effort. We are good like that.

Still. No getting pregnant, please.

[amazonsun.livejournal.com]

Hee!

Learning stuff is very good. :) Working an office job too, I always have those weird and random questions come up. I'm really looking forward to seeing what other questions will be posted. And I'm glad there are non-native English speakers here too - a different perspective on the whole thing.

But of course....now I'm super-paranoid about making a typo here! *giggle*

[roadrunner1896.livejournal.com]

I always have the excuse of being German. :D

[amazonsun.livejournal.com]

Ah....you're using it as an excuse now! I see how you are! :P

[roadrunner1896.livejournal.com]

You can see amazing? Because that is how I am.

[amazonsun.livejournal.com]

Yes...because I'm like a superhero with my visual powers of observation!

[roadrunner1896.livejournal.com]

Awesome.

[theemdash]

The good news is that all the red ink will wash off. ;)

[amazonsun.livejournal.com]

Oh good! I feel much better now. ;)