I have recently learned about infinitives. I know that infinitives act as nouns in the sentence rather than verbs, and that most infinitives are 'to + verb'.

Now bare infinitives have created a lot of confusion. Majority of the websites mention that bare infinitives act as main verbs after the auxiliary verb. My confusion is why we call them infinitives if they act as verbs? Or can bare infinitives work as a noun or noun phrase?

He does not sing well.

Does is an auxiliary verb in this sentence. So sing should be the main verb. But, infinitives don't act as verbs. Please help me clear up the idea of infinitives.

  • Infinitives are verbs. What else could they be? Infinitivals aren't nouns -- why would you think that?: In your example the infinitival clause "sing well" is complement to the tensed auxiliary verb "does"
    – BillJ
    Aug 10, 2020 at 6:15

3 Answers 3


The are called "infinitive" because they don't have inflections for tense or person. They use the bare form of the verb.
The verb forms called "auxiliary" are contrasted with "lexical" verbs. Using the verb from your example, the word "sing" is a lexical verb. When used alone, it changes with tense and person:
I sing
He sings
She sang

If "sing" is used with an auxiliary that is finite, it appears as a bare infinitival, because you can't have two finite forms in the same verb:
I can sing
He does sing
She did sing

In your example

He does not sing well.

the auxiliary "does" is a finite form. It is inflected for third person singular and present tense. The lexical verb "sing" appears as a bare infinitival that is its complement.

Student's Guide to English Grammar "bare infinitivals"

"In contrast to to-infinitivals, with their wide range of uses, bare infinitival clauses occur in only a very limited set of functions. They hardly occur except as internal complements of certain verbs, with no subject permitted"

(The reference contains some examples.)


Wikipedia explains this in depth, including a relatively comprehensive list of uses of infinitives in English, but here's a compact answer.

  • Infinitives do act as verbs - forming infinitive verb phrases
  • Infinitives are by definition non-finite, generally do not have a subject, and so form non-finite clauses. These may be used as nouns, adverbs, etc. The infinitive in these constructions is still a verb, even if the clause is being used as a noun.
  • Bare infinitives can be used as noun phrases: "What you should do is read the wikipedia article".
  • Infinitives are generally not modified for tense, person, or (in non-English languages) case.
  • 1
    I wouldn't go along with what you say. Infinitivals are not nouns (or adverbs). Just because they sometimes (but not always) occur in places where nouns hang out doesn't mean they are themselves nouns. In your example, "read the Wiki article" is an infinitival clause functioning not as a noun phrase, but as predicative complement of "be".
    – BillJ
    Aug 10, 2020 at 6:06
  • @BillJ, note that I do not say infinitivals "are" nouns, but rather that they "may be used as" nouns. Though technically they may not be nouns, adverbs, etc, they do seem to stand in for those things with some frequency. Is there a better way for me to phrase that, so the roles they play remain clear without misleading readers about their actual status? Aug 10, 2020 at 21:19

We can’t fully understand infinitive verbals without knowing what a verbal is. Verbs come in many forms. Sometimes these forms don’t function as a verb in a sentence; they might act as a noun, adjective, or adverb. When a verb form acts as a different part of speech, we call this a verbal.


Infinitives are a type of non-finite verb, which means it will never be the main verb of a sentence. Finite verbs are verbs that can be conjugated and used as the main verb.

Regarding your question, I found that the bare infinitive is not a noun, but rather a verb form. I don't know if you found the answer.

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