Japanese adjectives are either verbal adjectives or adjectival no

uns. Those in the first group, in their dictionary form, end only in -ai, -ii, -oi, or -ui, and are therefore sometimes called -i adjectives. Those in the second group have noun-like characteristics and when they modify nouns have the suffix -na and are sometimes called -na adjectives.

I-adjectives

An -i adjective can modify a following noun.

私は小さいねこを飼っています。
Watashi wa chiisai neko o katte imasu.
I have a small cat.

The stem of an -i adjective is formed by dropping the final -i, so that, for example, the stem of chisaii is chisai-. An -i adjective may be conjugated to give different tenses:

Present:
[stem] + -i
Past:
[stem] + -katta
Negative: [stem] + -kunai
Negative past:
[stem] + -kunakatta
Continuative: [stem] + -kute

The associated verb is in the present tense.

この本は面白いです。
Kono hon wa omoshiroi desu.
This book is interesting.

あの本も面白かったです。
Ano hon mo omoshirokatta desu.
That book was interesting too.

今日は寒くないです。
Kyou wa samukunai desu.
Today it’s not cold.

昨日も寒くなかったです。
Kinou mo samukunakatta desu.
Yesterday it wasn’t cold either.

この本は面白くて楽しいです。
Kono hon wa omoshirokute tanoshii desu.
This book is interesting and enjoyable.

na-adjectives

The -na adjectives can be used as predicates or as noun modifiers.

あの人は有名です。
Ano hito wa yuumei desu.
He is famous.

公園は静かではありませんでした。
Kouen wa shizuka dewa arimasen deshita.
The park wasn’t quiet.

静かな部屋がほしいです。
Shizukana heya ga hoshii desu.
I want a quiet room.

Colors

The following colour words may be used alone as adjectives:

赤い akai red 黄色い kiiroi yellow
青い aoi blue,green 黒い kuroi black
茶色い chairoi brown 白い shiroi white

When these words are used as nouns, the final i is dropped:

車は赤いです。
Kuruma wa akai desu.
The car is red.

赤はいい色です。
Aka wa ii iro desu.
Red is a nice colour.

The following colour words are nouns and must be followed with no:

茶色の chairo no brown 緑色の midoriiro no green
銀色の giniro no silver 紫の murasaki no purple
灰色の haiiro no gray 鼠色の nezumiiro no gray
黄色の kiiro no yellow オレンジの orenji no orange
金色の kiniro no gold

This page is a part of “Some Notes on Japanese Grammar” published for your personal use, with the kind permission of Keith Smillie (http://www.cs.ualberta.ca/~smillie/)