Sometimes, the exact same verb can express two different but closely related meanings:

  • The subject [S] is actually performing an action [V]
  • The subject [S] is capable of performing an action [V]

To illustrate this with a concrete example, contrast:

Birds that eat grains such as rice are categorized as... [taxonomic classification here]


Birds that eat grains such as rice don't actually explode afterwards.

In the first selection, the word "eat" is describing a characteristic of a certain category of birds: they have the ability to eat grains, regardless of whether or not they ever actually get the opportunity. So, a newly hatched fledgeling of whatever species might be a grain-eating bird without ever having actually eaten grains (or anything else).

In the second sentence, it's clear that "eat" refers to something the birds actually do, since there is a reference to the result of said action.

Is there a term for this distinction? It's not "aspect," but maybe something similar?

Another example of the 'potential' usage:

  1. Flying fish have large fins that act like wings to enable them to glide. There is a flying fish swimming in the water underneath our boat.

contrasted with the 'active' usage:

  1. Today there is forecasted to be a severe storm: watch out for flying debris and fish!

Within either context, the intended meaning is clear as being one or the other, but the usage differs for the same construction [i.e., 'flying fish'] between the two examples. The term I'm asking about (if it exists) describes what sets the usage in 1. apart from that in 2.

To satisfy the criteria for using the tag:

  • Sample sentence: "Just like the difference between 'sits' and 'is sitting' is one of aspect, the difference between 'V' in [some sentence] and [some other sentence] is one of [the word I'm looking for]."
  • Thesaurus/dictionary searches: Search terms like "potential vs actual action" and "action vs ability grammatical term" didn't turn up anything relevant. It's difficult to research a phenomenon when you don't know its name!
  • The "best" word: I'm looking for a grammatical term which has at least some official recognition.
  • What words I've considered, and why they don't work: "aspect" - doesn't fit; "causative vs. inchoative" - not the distinction I'm thinking of (this would be pairs like 'sit' vs. 'set' instead, which is not the same relationship)
  • Yes, it might also be a compound word or phrase - the 'single' part doesn't really matter.
  • 2
    I think the distinction you've made in "birds that eat" and "birds that eat" is specious. Neither is actual. Neither is capable.
    – TimR
    Commented Jul 6 at 0:52
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    One note: naming things in programming is, officially, off-topic for this site. We can answer the first part, but it may or may not work as a good term for use in code.
    – alphabet
    Commented Jul 6 at 1:27
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    sittable is the ability to be sat [by someone], not the ability to sit. Commented Jul 6 at 2:18
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    Please clarify the distinction you're trying to make. Both your first two examples refer to birds that can eat rice; they are in the present tense, but neither refers to birds that are eating rice at the time of the utterance.
    – Rosie F
    Commented Jul 6 at 5:46
  • 2
    ELL is for questions from learners -- it's for questions that would be too basic for ELU, because any native speaker would not have a problem. It's not for questions where other learners might know the answer because of insight from their native language.
    – Barmar
    Commented Jul 6 at 14:50

1 Answer 1


I understand the distinction you are making, but I am not aware of any single word to express the idea that is in common use. If someone else on here knows of such a word, I'll gladly yield. (Maybe it's just not coming to mind.)

If you want to express this idea, you have to use a phrase, like "potential versus actual" -- and then you'd likely have to explain what you meant.

I live in the Philippines and in one of the local languages here, Cebuano, there are actually different verb tenses for these two ideas. For example, "makakaon" means "is able to eat" but "nagkaon" means "is eating". But we do not have different tenses for this in English.

  • +1 for giving an example of a language which does use two separate forms! I'd guessed that might be the case but wasn't certain. Commented Jul 6 at 15:09
  • But we do have modals.
    – TimR
    Commented Jul 6 at 16:10
  • @TimR Yes, when I tried various search terms contrasting "actual" with "potential/ability," all the results showed modal constructions. I'm specifically asking about usages without auxiliaries like "can" and "able to." Commented Jul 6 at 16:13
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    @QuackE.Duck "Birds that eat grains such as rice" is a noun phrase in both instances, and it seems you want to distinguish between "eat" meaning "having as regular diet" and "eat" meaning "ingest" and assign a name to the nature of that difference in meaning.
    – TimR
    Commented Jul 6 at 17:00
  • @TimR Yes, exactly that! You've put it much more clearly than I did :D Commented Jul 6 at 17:34

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