This is the error I sometimes get when I try to go a website using an IP address instead of its proper domain name:

Fastly error: unknown domain: Please check that this domain has been added to a service.

I've been wondering as to what the expression fastly error really means? I've heard that fastly is not even a word in the English language, nevertheless it is obviously used by people who speak English as evident from my example. So, what are your thoughts?

  • 7
    "Fastly" is the name of a company that provides web services. It's not a regular English word at all.
    – John Feltz
    Dec 6, 2016 at 19:53
  • It has no meaning in standard English. Errors like this are almost always jargon created by an individual programmer, based on some kind of internal logic. To the programmer, "fastly" has some meaning, but without understanding the context, your guess is as good as mine. <Edit> or as John Feltz points out, it could be the name of a company. As I said, there is an internal logic, even if it's bad logic.
    – Andrew
    Dec 6, 2016 at 19:53
  • 4
    I'm voting to close this question as off-topic because it's about a proper name.
    – stangdon
    Dec 6, 2016 at 21:42
  • @stangdon: This is true, but it may be possible for a good answer to explain how it is that a fluent speaker can determine that it's simply a brand name used as an attributive noun and not an attempted adjective/adverb usage. Dec 6, 2016 at 22:06
  • @NathanTuggy - Well, that's a good point, although I would say a) how do you decide that, other than by saying, "Hmm, that word doesn't look like it makes sense there", and b) is this any different in English than it is in any other language? I mean, I could be reading Spanish and run across something saying "Error Rápidamente", and the process would be much the same...
    – stangdon
    Dec 6, 2016 at 23:28

1 Answer 1


As we can see from its -ly ending, fastly is an adverb (if it weren't a proper name). Error is a noun. Adverbs do not modify nouns, and so "fastly error" would be ungrammatical.

The namers of the company may have thought themselves clever, but their error message makes no sense to anyone who is not familiar with the company. The error itself seems an error.

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