Infinitive

sentence pattern
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On this page, you can learn about Japanese Infinitive which is 不定詞(ふ・てい・し)in Japanese.

Introduction

Here are examples of Infinitive. The basic format of Infinitive is ‘to + verb’.

  • I like to swim.
  • This is a pool to swim.
  • I go to pool to swim.

You can see ‘to swim’ in all the sentences but they work all in a different way.

Infinitive is divided into three groups, following how it works in a sentence. They are Noun Infinitive, Adjective Infinitive and Adverb Infinitive.

Noun, Adjective and Adverb

Before learning Infinitive, let’s learn what noun, adjective and adverb are.

Noun

Noun is a name of a thing which can be tangible or intangible.

Example of tangible

girl, robot, tennis, salt

Example of intangible

beauty, sadness, friendship, environment

Adjective

Adjective is for describing a noun. Its nickname is ‘describing word’.

Example

happy man, long boat, old house, something new

Adverb

Adverb is for describing a verb. Split the word ‘adverb’. You can see ‘ad (add)’ and ‘verb’. Adverb is the word whose meaning is added onto a verb.

Example

run fast, study hard, eat slowly, enjoy responsibly

Noun Infinitive: to + verb = verb + こと

Noun Infinitive is ‘to + verb’ which is used as if it’s a noun. You can consider it Noun Infinitive if you replace it with ‘a thing‘ and it still makes sense.

Amongst the three sentences below, which ‘to swim’ can be replaced with ‘a thing’?

  • I like to swim.
  • This is a pool to swim.
  • I go to pool to swim.
  • I like a thing.
  • This is a pool a thing.
  • I go to pool a thing.

Summary

The first one makes sense, so that is Noun Infinitive. Let’s revise the sentence pattern:

Noun Infinitive: to + verb = verb + こと

Here is the example of how to translate Noun Infinitive:

I like to swim.

わたし は およぐこと がすきです。

Exercise

Task: Change into Japanese.

  • My mother likes to talk with friends.
  • My hobby is to play baseball.
  • It is important to go to school.

Answer

Adverb Infinitive: to + verb = verb + ために

Adverb Infinitive is ‘to + verb’ which is used as if it’s an adverb. You can consider it Adverb Infinitive if you rewrite ‘to + verb’ with ‘because’ and it still makes sense.

Amongst the three sentences below, which ‘to swim’ can be written, using ‘because’?

  • I like to swim.
  • This is a pool to swim.
  • I go to pool to swim.
  • I like because I swim.
  • This is a pool because this swims.
  • I go to pool because I swim.

Summary

The third one makes sense, so that is Adverb Infinitive. Let’s revise the sentence pattern:

Adverb Infinitive: to + verb = verb + ために

Here is the example of how to translate Adverb Infinitive:

I go to pool to swim.

わたし は およぐために プール に いく。

Exercise

Task: Change into Japanese.

  • I go to Japan to study Japanese.
  • My older brother saved money to buy a car.
  • We came here to win a game.

Answer

Adjective Infinitive: to + verb = verb + ための

Adjective Infinitive is ‘to + verb’ which is used as if it’s an adjective. You can consider it Adjective Infinitive if you see it after a noun plus can’t rewrite ‘to + verb’ with ‘because’.

Amongst the three sentences below, which ‘to swim’ meets the two conditions?

  • I like to swim.
  • This is a pool to swim.
  • I go to pool to swim.

  • I like because I swim.
  • This is a pool because I swim.
  • I go to pool because I swim.

Summary

‘to swim’ in the second and third sentence come after a noun. However, the second one does not make sense when it is rewritten with ‘because’. Therefore, the second ‘to swim’ is Adjective Infinitive.

Adjective Infinitive: to + verb = verb + ための

Here is the example of how to translate Adjective Infinitive:

This is a pool to swim.

これ は およぐ ための プール です。

Exercise

Task: Change into Japanese.

  • I want something to drink.
  • I don’t know what to do.
  • This is a tool to open a can.

Answer

Extension

Adjective Infinitive: べき

べき is sometimes used instead of ための for Adjective Infinitive.

Example

Japan has a lot of places to visit.

日本 には おとずれる べき たくさんの場所 があります。