How to use I-Adjectives in Japanese

An Introduction to i-Adjectives in Japanese for Beginners

Welcome to our third video and article series with tutor Naomi. In this live-stream, Naomi explains briefly how to use i-adjectives in their normal, negative and polite forms.

I-adjectives are called that way because they always end on an “i” when placed before the noun they are modifying. First, let’s take a look at two i-adjectives that are used quite frequently.

暑あつい

Hot

寒さむい

Cold

To convert i-adjectives into their polite forms, simply add “です” at the end:
暑あついです寒さむいです “です” can only be added when the adjective is placed at the end of the sentence, not when it is used to modify a noun. If you want to make a polite sentence with an i-adjective as a noun modifier, you can put “です” after the modified noun. E.g.: I-adjective as a noun modifier (polite):

今日きょうは暑あつい天気てんきです。

The weather is hot today.

I-adjective at the end of a sentence (polite)今日きょうは暑あついです。
It’s hot today.
If you would like to talk about your own sensation of the weather, you can simply add “わたしは” before the adjective, but it may send more natural not to:

わたしは暑あついです。

I feel hot.

わたしは寒さむいです。

I feel cold.

If you are talking to a friend, these are more natural ways to express your sensation of the weather:

今日きょう暑あついね！

It’s hot today!

最近さいきんけっこう寒さむいね。

It’s quite cold recently.

今日きょう暑あつくない？

Isn’t it hot today?

寒さむいのはもう嫌いやだ！

I’m done with the cold!

Now, to express the negative of an i-adjective, you replace the “い” at the end with “くない”:

暑あつくない

Not hot

寒さむくない

Not cold

Again, if your adjective is at the end of the sentence you can add “です” to make your sentence polite. If you use the adjective to modify a noun, again, please add “です” after the noun.
I-adjective as a noun modifier (polite, negative):

今日きょうは寒さむくない日です。

Today is not a cold day.

I-adjective at the end of a sentence (polite, negative):

今日きょうは寒さむくないです。

Today is not cold.

Here are a few more example sentences from Naomi’s stream:

これから寒さむくなりますね。

It’s going to get colder from now on.

京都きょうとは今日きょうも寒さむいです。

It is cold in Kyoto today as well.

昼ひるは暑あついです。

It is hot at noon.

今いまは暑あつくないです。

It’s not hot right now.

That’s it for today. If you have any questions, you can always clear them up by booking a lesson with one of our native Japanese tutors. See you next time!

単語たんごリスト（Vocabulary list）

い形容詞けいようし	I-adjective
否定文ひていぶん	Negative sentence
天気てんき	Weather
今日きょう	Today
京都きょうと	Kyoto
昼ひる	Noon