Is the infinitive marker 'to' a preposition?

No, it is a grammatical particle. Although it shares spelling with the preposition 'to', it does not indicate direction or location; it only signals the infinitive verb form.

When is the infinitive marker omitted?

It is omitted after modal verbs (can, will, must, etc.), after the verbs 'let', 'make', 'help' (especially in AmE), and after perceptive verbs like 'see' and 'hear' when followed by an object and the base verb (e.g., I saw him leave).

What is a 'split infinitive'?

A split infinitive occurs when an adverb is placed between the infinitive marker 'to' and the base verb (e.g., 'to boldly go'). Once frowned upon, it is now generally accepted in modern usage when it improves clarity or rhythm.

Can 'to' ever be part of a phrasal verb and an infinitive marker at the same time?

No. In structures like 'look forward to seeing you', the 'to' is a preposition, part of the phrasal verb 'look forward to'. It is followed by a gerund (-ing form), not a base verb, so it is not functioning as an infinitive marker.

infinitive marker

UK/tə/ (weak form), /tuː/ (strong form)US/tə/ (weak form), /tu/ (strong form)

Technical / Formal / Academic

My Flashcards

Definition

Meaning

A function word, typically 'to', placed before the base form of a verb to signal the infinitive construction (e.g., 'to go', 'to be').

In linguistic terminology, it denotes the particle or morpheme that introduces the infinitive form of a verb in a syntactic construction. It is a grammatical marker, not a preposition, although it shares a form with the preposition 'to'.

Linguistics

Semantic Notes

The term is used primarily in grammatical description and language teaching. It refers to a syntactic role, not a lexical item with independent meaning. The marker 'to' is often omitted after modal verbs and certain causative/perceptive verbs (e.g., 'can go', 'let him go').

Dialectal Variation

British vs American Usage

Differences

No significant difference in the grammatical concept or core use. Minor variation in the verbs that trigger 'bare infinitive' constructions (e.g., BrE 'help someone to do', AmE 'help someone do').

Connotations

None.

Frequency

Equally frequent in grammatical discussions within their respective dialects.

Vocabulary

Collocations

strong

precedes thefollowed by aomission of thefunction of the

medium

introduces the infinitiveacts as anuse thesignals the

weak

grammaticallinguisticsyntactic

Grammar

Valency Patterns

VERB + infinitive marker + base verb (e.g., want to leave)ADJECTIVE + infinitive marker + base verb (e.g., happy to help)NOUN + infinitive marker + base verb (e.g., decision to resign)

Vocabulary

Synonyms

Strong

'to' (in context)

Neutral

infinitive particle'to'-particle

Weak

infinitive sign

Vocabulary

Antonyms

bare infinitivefinite verb marker

Phrases

Idioms & Phrases

“Splitting the infinitive (deliberately placing an adverb between 'to' and the verb)”

Usage

Context Usage

Business

Used when discussing plans or intentions (e.g., 'Our aim is to expand').

Academic

Central to syntactic analysis in linguistics papers.

Everyday

Implicitly used in countless utterances; the term itself is rarely used.

Technical

Defined and analysed in grammar textbooks and linguistic literature.

Examples

By Part of Speech

verb

British English

We need to practise more regularly.
I'd like to pop to the shops.

American English

We need to practice more regularly.
I'd like to stop by the store.

adverb

British English

He arrived early to get a good seat.
I called to confirm the booking.

American English

He arrived early to get a good seat.
I called to confirm the reservation.

adjective

British English

She was delighted to receive the honours.
It's important to queue properly.

American English

She was delighted to receive the honors.
It's important to line up correctly.

Examples

By CEFR Level

I want to eat.
He likes to sing.

She asked me to help her with the project.
It's nice to meet you.

The government pledged to invest in renewable energy sources.
He is known to be a very reliable colleague.

The committee's refusal to countenance the proposal was deemed politically motivated.
To err is human; to forgive, divine.

Learning

Memory Aids

Mnemonic

Think of it as a 'launch pad' (TO) for the verb's action into the sentence.

Conceptual Metaphor

A PATH or GATEWAY: 'to' marks the pathway to the verbal action.

Watch out

Common Pitfalls

Translation Traps (for Russian speakers)

Russian infinitives are single words ending in -ть, -ти, -чь, so the concept of a separate 'marker' is alien.
Do not confuse the infinitive marker 'to' with the preposition 'to' indicating direction (к).
Avoid inserting 'to' after modal verbs like 'can' or 'must' as in Russian structure.

Common Mistakes

Using the infinitive marker after modal auxiliaries (*'I must to go').
Omitting the infinitive marker after adjectives of intention (*'I'm ready go').
Confusing it with a preposition and using an -ing form (*'I look forward to see you').

Practice

Quiz

Fill in the gap

After 'let' or 'make', we do not use the .

Multiple Choice

In which sentence is 'to' an infinitive marker?

FAQ

Frequently Asked Questions

: No, it is a grammatical particle. Although it shares spelling with the preposition 'to', it does not indicate direction or location; it only signals the infinitive verb form.
: It is omitted after modal verbs (can, will, must, etc.), after the verbs 'let', 'make', 'help' (especially in AmE), and after perceptive verbs like 'see' and 'hear' when followed by an object and the base verb (e.g., I saw him leave).
: A split infinitive occurs when an adverb is placed between the infinitive marker 'to' and the base verb (e.g., 'to boldly go'). Once frowned upon, it is now generally accepted in modern usage when it improves clarity or rhythm.
: No. In structures like 'look forward to seeing you', the 'to' is a preposition, part of the phrasal verb 'look forward to'. It is followed by a gerund (-ing form), not a base verb, so it is not functioning as an infinitive marker.