Temporary reopen note:

This question may appear at first blush to be about whether to use who or whom. However, the naturalness and grammaticality of this phrase has to do with the periphrastic genitive versus the saxon genitive, not whether to use nominative or accusative case. For this reason this is both a useful question and not a duplicate of the linked-to post here:

The Question:

Just to give a few details: I am writing an answer to an exercise, the exercise describes arranged objects, I want to state that the provide information allows one to deduce what are the neighboring objects.

How do I say it in one sentence - "who are the neighbors of who?" It does not sound correct to me...

I would appreciate it if someone could point out if this is correct and would be grateful if there is a way to break this down or compare it with similar language construction to help me get familiar with this type of sentence.

  • 2
    "Who are neighbours to whom?"
    – Mick
    Commented Dec 29, 2016 at 19:45
  • "... allows us to determine who are whose neighbors" might work.
    – Hellion
    Commented Dec 29, 2016 at 19:46
  • 1
    For a simple question, perhaps "Who has which neighbors?"
    – Hellion
    Commented Dec 29, 2016 at 19:52
  • 1
    @Araucaria: "After a preposition there usually is no choice, we have to use whom." There are enough exceptions to that statement that I would not teach it as a general rule. In phrases like "knowledge of who was in the film" "whom" is actually impossible since the pronoun is not the object of the preposition, despite coming after it. Also, I wouldn't say "whom" is required in questions that don't use fronting, like "Have you ever heard of him?" "Have I ever heard of who"?...
    – herisson
    Commented Dec 30, 2016 at 4:01
  • 4
    @Araucaria: If you look at Google Ngram Viewer, "of who" is definitely less frequent than "of whom", but not overwhelmingly so in modern writing.
    – herisson
    Commented Dec 30, 2016 at 4:01

3 Answers 3


In a situation where all the people are indefinite (perhaps all the people in a neighborhood or a clan), one can use who after a preposition like that. The basic fixed phrase is

  • Who is who (in this picture)? [not whom; usually contracted to Who's who?]

  • Who's standing next to who in this picture? [whom is allowed but infrequent]

The rule for whom says it's never required, except when it's the object of a pied-piped preposition. Other prepositions, like these, can use who or whom, no difference in meaning, only falutation.


It would be "who are the neighbors of whom" because though who and whom come from the same root word, "who" is properly used as a subject (like "I", "he", or "she") and "whom" is used properly as an object (like "me", "him", or "her").


The provided information allows one to say of the objects which neighbors which.

The sentence above completely skirts the singular-plural issue. It handles both because the relationship is a reciprocal one.

The provided information allows one to say of the objects which is neighbors with which.

That sentence has a singular verb too but to get caught up in that would be silly in the given context: the cumulative effect is that all neighbor relationships can be established.

The discussion below is for people, not things, but will support the second example I've given above.

who is neighbor of who? is idiomatic colloquial American English.

Your version with the plural is marginal, to my ear: Who are the neighbors of who? Why? Not because the number agreement is ungrammatical, not at all, as it isn't, but because that's not how the question is asked in colloquial contexts. It "mixes registers".

On the singular/plural issue... Each "who" may have multiple neighbors, true, but the singular version I gave above doesn't preclude that possibility, and it is far more likely to come out of the mouths of native American English speakers speaking casually than your plural version.

At this level of colloquialism, even the verb is can refer notionally to more than one person especially if they can be subsumed under a role. (In Who is neighbor of who? the word neighbor without article is being used as a role.) We could be talking, say, about couples living in a neighborhood, and someone listening in and trying to keep straight in their mind which couples are neighbors of which, might ask "Who is neighbor of who?" or even "Who is neighbors of who?"

An example of what may seem to be the chimerical nature of number agreement in this particular colloquial context with neighbors is the following:

In this article, the numerical order is used to determine which numbers are neighbors. As an example, the number 3 is neighbors of 2 and 4.

But let's go one step further and make it a circle, 0-9 and back to 0 (01234567890123...). With that, the number 9 is neighbors of both 8 and 0. And 0 is neighbors of both 9 and 1. [my emphasis]

But there, neighbors is not so much a plural noun as it is a predicative complement that means "being in the role of neighbor". (Compare "is partners with" here.)

And so a perfectly idiomatic normal-register version of your question that accommodates a notionally singular or plural subject is:

Who is neighbors with who?

with this version being in formal register:

Who is neighbors with whom?

NOTE: I said with who(m) there since that preposition is in the linguistic thal-weg, so to speak, of this predicative use of neighbors.

Note: That predicative use is neighbors is not an Americanism.

There are people who will see of who as wrong, and think whom is the correct choice. I can't tell you what to do about that issue. whom is what educated people would probably write when trying to be formal and correct, especially if they don't want to risk being tagged as uneducated. Moreover, even if the author were to have written "with who", in many journals the editorial staff would red-pencil it and replace it with "with whom". Written attestations are to some extent artificial in that they reflect editorial preference not actual usage.

Here's an illuminating contrast:

Who's kidding who? (from Creative Pastors)

Who's kidding whom? (from National Library of Medicine)

The irony there is that the author (editor?) of the article in the National Library of Medicine is using the "correct" whom, which has been falling out of use for centuries and is largely moribund in colloquial speech, in a colloquial phrase, violating the "register" . It's like saying "Who's punking whom?" or "Who's ghosting whom?"

  • Please cite sources for this. To me, "who is neighbor of who?" sounds totally wrong, even if you add a determiner to "neighbor." I would, like the asker, only use the plural here, even speaking colloquially (as a fellow native AmE speaker).
    – alphabet
    Commented Aug 24, 2023 at 4:13
  • Neighbor is treated there as a "role noun". You will find this use especially in books related to Christian ministry.: *Who is neighbor to me ? " Jesus answers his question and more;" But that's just a ready example and there should be no problem finding plenty more examples of that role usage.
    – TimR
    Commented Aug 24, 2023 at 9:50
  • english.stackexchange.com/questions/534612/…
    – TimR
    Commented Aug 24, 2023 at 10:18
  • @TimR Am I my brother's neighbour? Commented Aug 24, 2023 at 10:36
  • @EdwinAshworth I suppose it depends on where he lives and on whether you are a boor (etymological joke)
    – TimR
    Commented Aug 24, 2023 at 10:57

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