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Past Tense of Japanese Adjectives

To study this grammar point, please make sure you understand the following:

In English, you do not need to change an adjective to another form for past tense. In Japanese, however, an adjective is like a verb, and you will need to change to its modified past-tense form.

Rules for Deriving Positive Past Tense of Japanese Adjectives

In general, the plain past tense form is:

  1. For だ (a noun or a noun-like な-adjective), change it to だった.
  2. For い, change it to かった.

Examples for な-adjectives:

  • げんきな → げんきだった (was healthy)
  • すきな → すきだった (liked)
  • しずかな → しずかだった (was quiet)
  • べんりな → べんりだった (was convenient)

Examples for い-adjectives:

  • おおきい → おおきかった (was big)
  • あつい → あつかった (was hot)
  • おもしるい → おもしるかった (was interesting)
  • あかい → あかかった (was red)
  • いい → よかった (was good)

Some example usages:

A person who was big.
A person who was healthy.

The rule for negative past tense is relatively simple, as all the negative present tense adjectives are い-adjectives, so you can apply the rules for い-adjectives for negative past tense.

Rules for Deriving Negative Past Tense of Japanese Adjectives

Examples of な-adjectives:

  • げんきな → げんきじゃない → げんきじゃなかった (was not healthy)
  • すきな → すきじゃない → すきじゃなかった (disliked)
  • しずかな → しずかじゃない → しずかじゃなかった (was not quiet)
  • べんりな → べんりじゃない → べんりじゃなかった (was not convenient)

Examples of い-adjectives:

  • おおきい → おおきくない → おおきくなかった (was not big)
  • あつい → あつくない → あつくなかった (was not hot)
  • おもしるい → おもしるくない → おもしるくなかった (was not interesting)
  • あかい → あかくない → あかくなかった (was not red)
  • いい → よくない → よくなかった (was not good)

Some example usages:

A person who was not big.
A person who was not healthy.

Polite Form of Japanese Adjectives

When you look up words in a dictionary, they are written in plain form which you would say casually in your daily life.

Polite Form for い-adjectives

You may change an an い-adjective phrase to polite form by adding です (polite form of verb to be) at the end of the sentences. Of course だ (plain form of verb to be) should be dropped, if it exists. It applies for present, negative and past tense forms.

Polite Form for な-adjectives

For な-adjectives, treat it like a noun and apply the same rules as the conversion between verb to be だ and です.

Introduction to Japanese Adjectives

To study this grammar point, please make sure you understand the following:

Adjectives are used to modify nouns. There are 2 types of adjectives, namely な-adjective (na-adjective) and い-adjective (i-adjective), in Japanese grammar.

You need to be able to distinguish between な-adjectives and い-adjectives because they have different rules for their modified forms.


By attaching な to the end of some noun, it becomes a な-adjective.

When you look up the dictionary, for instance, 元気 (/genki/ health) is both a noun (名) and an adjectival verb (形動). That means it is a な-adjective, and you can use it to modify another noun.

A healthy person.
(a person who is healthy)

The stem of a な-adjective is a noun (without the suffix な). This is the base for all other modified forms of the adjectives.

Examples of な-adjectives:

Hiragana Pronunciations Definitions Kanji Stem
げんきな /genkina/ healthy 元気な 元気
すきな /sukina/ to like 好きな 好き
しずかな /shizukana/ quiet 静かな 静か
べんりな /benrina/ convenient 便利な 便利


An い-adjective always ends with a hiragana suffix い. It is specified as adjective (形) in a dictionary.

A big person.
(a person who is big)

The stem of an い-adjective is the adjective without the suffix い. This is the base for all other modified forms.

Examples of い-adjectives:

Hiragana Pronunciations Definitions Kanji Stem
おおきい /ookii/ big 大きい 大き
あつい /atsui/ hot 暑い
おもしろい /omoshiroi/ interesting 面白い 面白
あかい /akai/ red 赤い

One major difference between い- and な-adjectives is that, the stems of な-adjectives act like nouns, but い-adjectives do not have such a property.

As a result, for many modified forms, だ needs to be attached to な-adjective, but never to い-adjective.

Never attach だ to い-adjectives.

Notice that some な-adjective, for example, きれい (/kirei/ clean), looks like an い-adjective. But if you look up the word in kanji, it is writen as 綺麗, and it does not have an い suffix. So it cannot be an い-adjective.

On the other hand, some adjective stems can serve as both い- and な-adjectives. For example, 大きい and 大きな are both common adjectives in Japanese.

Particle で for Methods and Ways

To study this grammar point, please make sure you understand the following:

Particle indicates methods or ways to accomplish an action, can be translated as by means of in English.

Let’s go by car.
I wrote the letter in Japanese.

Particle や for Item Listing

To study this grammar point, please make sure you understand the following:

Like particle と, is used to list one or more nouns, but particle や implies that there may be other things that are unlisted and that not all items in the list may apply.

Buy (things like) books and magazines, etc…

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