A friend of mine wrote me this:

I understand everything (what) you write.

I mentioned that it was probably better to write 'that' instead of 'what´. We were not able to find the correct answer, partly because it is not our mother tongue.

  • I'm flagging this as off-topic ("belongs on ELL"). Hi Gerda, you may not be aware that this EL&U site is for "linguists, etymologists, and serious English language enthusiasts", whereas your question is probably more suited to our other site English Language Learners. If you have a question for ELL, be sure to read their guidance on what you can ask. :-) Feb 1, 2019 at 3:36
  • Please do not close: edit. There is a really good question here. Feb 1, 2019 at 21:14
  • 1
    Possible duplicate of Use of "what" vs "that"
    – shoover
    Feb 1, 2019 at 21:17
  • @shoover puhlease. The answers there are inadequate; Colin Fine's answer here should be the archival answer. Feb 1, 2019 at 21:20
  • 'Everything what you right' sounds like Estuary English (that is, it is not standard English, but in some dialects it is how you say it).
    – Mitch
    Feb 13, 2019 at 14:38

1 Answer 1


What can be used as a fused relative pronoun - the equivalent of "that which". So "I understand what you write" is grammatical and idiomatic.

You are trying to use it as a relative pronoun or subordinator, qualifying everything. This is common in some varieties of English, but not (as far as I know) in any standard varieties. So "I understand everything what you wrote" is not grammatical in standard English. (For a well-known example of this non-standard usage, see The Play What I Wrote, a play about comedy double acts. The title is a catch phrase that the duo Morcambe and Wise used in their show, which was deliberately non-standard for comic effect. )

So you need to follow "everything" with either a separate relative pronoun ("which") or a subordinator ("that") - or nothing, because where the relative pronoun is not the subject of the relative clause, you can omit it.

I would say these are in reverse order of naturalness, so the most natural form in speech is

I understand everything you write.

The next most common, and slightly more formal, is

I understand everything that you write.

The third possibility, while grammatical, is less usual:

I understand everything which you write.

(You may find people who say that you can't use "which" in a restrictive relative clause. They are wrong. Oliver Kamm says in Accidence Will Happen: "One thing you won't find in style guides that advocate the that/which rule is the slightest substantiation for it").

  • I had a discussion about this here on ELU a few years back (I'll see if I can find it, but I don't think there's a way to search in comments), where somebody persuaded me with some difficulty that that is not a relative pronoun, but a subordinator that in many contexts can replace a relative pronoun.
    – Colin Fine
    Jan 31, 2019 at 18:57
  • Here is a thread where I referred to the previous discussion!
    – Colin Fine
    Jan 31, 2019 at 19:01
  • The comments here indicate that this analysis is to be found in CGEL. I wish I could find the comment thread here where somebody convinced me.
    – Colin Fine
    Jan 31, 2019 at 19:09
  • There's plenty of evidence to support the claim that "that" is a subordinator, not a relative pronoun. For instance, "the patients to whom the letter was sent" is grammatical but *"the patients to that the letter was sent" is of course not. If "that" were a relative pronoun, the latter would be grammatical.
    – BillJ
    Jan 31, 2019 at 19:15
  • 1
    Found it, @KannE! My conversation with Aaron in the comments to my answer to this question
    – Colin Fine
    Jan 31, 2019 at 19:15

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