Understanding infinitive verbs: what they are and how to spot them in sentences

Outline

• Hook: Infinitives are small words with big reach in English.

• What is an infinitive? Define it as the base form of a verb, usually with to in front. Note the occasional bare infinitive after certain verbs.

• How infinitives work: as nouns, adjectives, or adverbs; with fresh examples.

• Reading and writing tips: how to spot infinitives in text and use them clearly.

• Quick practical notes for English assessments (like the Accuplacer): recognizing purpose, intention, or action without getting bogged down in tense.

• Short practice: a tiny exercise to identify infinitives in sentences.

• Warm close: a nudge to keep exploring grammar in a natural, human way.

To, or not to, the infinitive? A friendly guide to a tiny but mighty verb form

Infinitives may be small, but they show up everywhere. Think of “to run,” “to eat,” or “to observe.” That little “to” is doing a big job, giving us a non-finite form of the verb that can do a lot in a sentence. If you’ve ever seen a sentence where the verb doesn’t seem tied to a tense or a subject, chances are you’re looking at an infinitive or a close cousin called a bare infinitive. Let me explain how these work, why they matter, and how to spot them when you’re reading or writing—whether you’re navigating English language assessments or just trying to sound a bit more precise.

What exactly is an infinitive?

Here’s the thing: an infinitive is basically a verb in its base form, most often preceded by the word to. So you get to run, to eat, to observe, to think. That “to” is a hint that we’re not talking about a finished action tied to a subject with a specific tense. It’s a non-finite verb form, which means it doesn’t tell you who is doing the action or when the action happens in the same way a finished sentence does.

Now, you’ll also hear about bare infinitives. Those are infinitives where the to is missing after certain verbs, like help, let, make, or some phrases after verbs of perception (see, hear) in certain constructions. For example:

• I want to help you cook dinner. (to cook)

• Let him go. (go, no to)

• She helped me understand the problem. (understand, no to)

So while “to + base form” is the usual recipe, there are tasty little exceptions that pop up in everyday speech and writing. The important takeaway is that infinitives are versatile: they don’t carry tense themselves, and they can slip into different roles in a sentence.

Infinitives can wear many hats

Infinitives aren’t shy—they jump into sentences in three main jobs: as nouns, adjectives, or adverbs. Here are simple illustrations to spot each use.

• Infinitive as a noun

• To forgive is human.

• The goal is to learn, not to brag.

In these cases the infinitive acts like a noun, naming the action itself.

• Infinitive as an adjective

• He has a plan to win the game.

• This is a book to read in one sitting.

Here the infinitive describes a noun (plan, book), giving more detail about what that noun is about.

• Infinitive as an adverb

• She paused to think before answering.

• I opened the door to let in some light.

In these examples the infinitive explains why something happened, or what the purpose was.

A quick caution about prepositions

Sometimes the word to serves as a preposition, not part of an infinitive. In a sentence like “I went to the store,” to is a preposition pointing to a place, not a to + verb infinitive. The clue is whether the word to is directly followed by a verb that would make sense as “to [verb].” If it does, you likely have an infinitive; if not, it’s a prepositional phrase.

Why this matters for reading and writing

Understanding infinitives helps you read more clearly and write with greater nuance. They let you express purpose (“I came here to study”), intention, or even a kind of abstract idea in a compact way. When you’re looking at sentences on language assessments or in reading passages, spotting infinitives can help you understand what a sentence is really doing—whether it’s naming an idea, qualifying a noun, or explaining a motive.

Tips for spotting infinitives in text

• Look for the “to” that sits right before a verb. If you can swap in a form of to + verb and it still sounds natural, you’ve likely found an infinitive.

• Check whether the phrase answers “why” or “for what purpose.” If yes, that’s a good sign you’re looking at an infinitive of purpose.

• Distinguish from a prepositional “to” by asking what comes after it. If what follows is a verb, you’re probably seeing an infinitive.

• Be aware of bare infinitives after certain verbs. If you see a verb following a verb of permission, causation, or perception (let, make, help, see, hear), the to might be omitted.

Infinitives in the context of English assessments

In many English language assessments, including those used for college placement, you’ll encounter passages where infinitives show up in various guises. The goal isn’t to memorize every rule in a vacuum; it’s to recognize how infinitives function in real sentences. A clear sense of infinitives helps you parse sentence structure quickly, identify how ideas are linked, and recognize whether a sentence is aiming to describe purpose, state, or action without getting tangled in tense.

A practical, human-friendly checklist

• Is the phrase a simple “to + base form” verb? If yes, you’re looking at an infinitive.

• Does the phrase act as a noun, an adjective, or an adverb? If you can justify one of those roles, you’ve labeled its function correctly.

• Are there words around it that signal purpose or intention? If so, the infinitive is likely doing that job.

• Is there a moment where the “to” is missing after a controlling verb? That would be a bare infinitive.

• Does the phrase connect to a noun as a descriptor? That’s the adjective role.

• Does the phrase explain why something happened? That’s the adverb role.

A tiny exercise to try on your own

Read these sentences and spot the infinitives:

1. She decided to join the club because she wanted to meet new people.

2. The plan to finish early impressed the team.

3. They watched the sun rise to greet the day.

4. Let him go, and you’ll see what happens.

Answers:

1. to join (infinitive as part of a purpose clause)

2. to finish (infinitive functioning as an adjective describing the plan)

3. to greet (infinitive describing the purpose of watching)

4. go (bare infinitive after let)

A gentle nudge toward stronger command of the language

Infinitives are a backbone of clear expression. They let you shift focus—from the action itself to the purpose behind it. They give your sentences a sense of direction. They invite you to tell a story not just about what happened, but why it happened and what it was meant to accomplish.

If you’re curious, you can explore a few ways English writers use infinitives in everyday life:

• In interviews or essays, you’ll often see purpose expressed with to: “I’m learning to communicate better.”

• In descriptions or instructions, infinitives help you lay out steps or goals succinctly: “To mix the batter, whisk eggs and sugar.”

• In persuasive writing, infinitives can sharpen intent: “To save you time, we’ll skip the fluff and get to the point.”

Common missteps to avoid

• Overloading sentences with too many infinitives in a row can make writing feel cluttered. Mix in nouns and independent clauses to keep rhythm.

• Confusing to as a preposition with to as part of the infinitive. When in doubt, test the verb after to: does it form a natural “to + verb” pair?

• Forgetting that infinitives can act as adjectives or adverbs can cause you to misplace a phrase. If a phrase is describing a noun or explaining a verb, you might be looking at an infinitive used in a non-noun role.

A final thought

Language is a living tool, and infinitives are one of its most flexible handles. They’re short, but they can carry big meaning, a bit like a micro-connector in a sentence engine. By recognizing the telltale “to + base form” pattern and watching how infinitives behave across different roles, you’ll glide more confidently through reading passages and writing tasks alike.

If you’d like to keep digging into grammar in a natural, human way, a few respected sources offer clear explanations and plenty of examples—without drowning you in jargon. And as you read, you’ll start to notice how real writers thread infinitives into sentences to express purpose, nuance, and meaning with ease.

In short: infinitives aren’t just grammar trivia. They’re a practical, everyday tool that helps you explain why things happen, what you intend to do, and how ideas connect. Keep an eye out for that tiny “to” in front of a verb, and you’ll unlock a cleaner, more flexible way to express yourself in English.

If you’d like to explore more about grammar in a conversational way, I’m happy to suggest friendly resources or quick, light-read explanations that keep the flow going without turning every paragraph into a textbook chapter.