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Types of things vs. types of thing

When using the phrase "types of" or "kinds of," it often seems appropriate to follow with a singular noun (e.g., types of rock), but at other times a plural noun sounds better (e.g., types of sentences). Is there some kind of rule about this?

  • 1
    @Robusto Do feel free to edit or let me know if my answer is way off the mark... Seemed to me a relatively simple question about count and mass nouns but the other related question delves into a lot of nuance in which forms different speakers use for the overall class of "thing" :)
    – aedia λ
    Jun 14, 2011 at 20:37
  • @Robusto - is there any way to provide a link there to the answers here? @aedia 's answer is particularly informative.
    – Dave
    Jun 14, 2011 at 23:14

3 Answers 3


I think your essential concern is about countable vs. uncountable nouns. Countable nouns can be singular or plural; uncountable nouns are singular. Some words can be both, in different meanings.

Take a look at this example discussing countable and uncountable nouns:

The coffees I prefer are Arabica and Brazilian. (Here coffees refers to different types of coffee)

You could write, "The types of coffee I prefer are Arabica and Brazilian."

So with your example:

The rocks I like are basalt and granite. [Rocks are countable]

The types of rock I like are basalt and granite. [Rock is uncountable]

When rock is taking on the uncountable meaning, it's not one rock - it's the idea of rock, the general concept. The only senses in which this is familiar to me are the "solid mineral" one and rock as in "rock music," where you might say, "The types of rock I like are grunge and punk."

Contrast the other part of your example:

The sentences I like are about geology. [Sentences are countable]

The types of sentences I like are about geology. [Sentences are still countable]

Sentences don't have an uncountable meaning:

*The types of sentence I like are about geology. [Ungrammatical for most speakers, I think]

  • are you saying that the uncountable version should be used whenever possible, otherwise the countable version should be used? the reason I ask is that "The types of rocks I like are basalt and granite," doesn't sounds that strange to me. Apr 18, 2013 at 18:47
  • Take a look at the linked duplicate question and @Kosmonaut's accepted answer: "there is generally number concord between the type-word and the class itself". A word like detergent seems to work like rock: it can be countable or uncountable, so if it's taking on a countable meaning, you can say the types of detergents I like are Tide and Wisk; uncountable: the types of detergent I like are Tide and Wisk. For me, I think that if I use types or kinds, I pick the uncountable meaning - what types of rock do you like? and vice versa: what kind of rocks do you like?
    – aedia λ
    Apr 18, 2013 at 19:48
  • As the linked question shows, there's also variation between British and American English. I speak AmE and I don't think I would ever say there are two types of apple, as a BrE speaker in the linked question mentions is perfectly grammatical there. To answer your original question, I don't think there is a rule that you should always prefer the uncountable or countable meaning, when a word can have both.
    – aedia λ
    Apr 18, 2013 at 19:56
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    (Unlike there are two types of apple, which is jarring to my American English ear, I don't think I would be surprised to hear the types of rocks I like are basalt and granite. There is a slight difference: emphasis on the separate rocks, rather than rock as a class. I might expect the context to show that you're referring to a more specific rock: the types of rocks I like are basalt and granite ones like these.)
    – aedia λ
    Apr 18, 2013 at 20:04

Here's a rule of thumb with which to decide the correct usage in any given case.

Turn the phrase around:

I like all kinds of music = I like music of all kinds

I like all kinds of apple ≠ I like apple of all kinds

I like all kinds of apples = I like apples of all kinds

And so on.

  • What does "/=" mean?
    – fbessho
    Dec 19, 2017 at 22:19
  • 1
    @fbessho it means "not equal to"
    – Andrew
    Nov 5, 2018 at 19:51
  • This doesn't actually have any logic to it. In your first column, you have "of music": in your second column, you have "of ... kinds". This is not a simple word-order type of inversion: you have changed the grammar as well. You can't make any grammatical deductions based on this. Apr 17, 2021 at 10:43

Good question. There may not be a hard and fast rule other than what sounds better, and I probably won't explain this right, but "types of [singular]" is generally a label that implies a division within a general class noun, while "types of [plural]" is generally a label that implies a grouping of individual items.

"Types of metal", for instance, indicates that you are attempting to discern between various varieties of materials that, in general, are referred to or described as "metal". These types, possibly referred to by their elemental or common names (lithium, iron, magnesium, and alloys like steel), are "metals", plural. To say "types of metals" indicates an attempt to regroup these individual variants under headings more general than their basic names, but less generic than the overall concept "metal". To illustrate: "Gold is a type of metal, belonging to the transition metals". Gold is identified in the singular as a variant of the basic class of metal, then grouped with other types of metal to form a type of metals.

Confused yet? Again, probably no hard and fast rule, but after some thought, this was the best I could come up with.

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