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.

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