What it means
い-adjectives describe qualities such as size, temperature, difficulty, or appearance. They can directly predicate a sentence and can also come before a noun without an extra word. Their final い changes for negative and past forms. In polite sentences, the adjective form stays the same and です is added after it. The く form is used before certain endings and when the adjective modifies a verb.
Usage note
Do not treat every adjective ending in い as an い-adjective. For example, きれい and ゆうめい are な-adjectives. The adjective いい is irregular: its common changed forms use よ, such as よくない and よかった.
How to use it
昨日、新しい靴を買いました。
Yesterday, I bought new shoes.
私の犬は大きいです。
My dog is big.
昨日の試験は難しかったです。
Yesterday's test was difficult.
この料理は辛くありません。
This dish is not spicy.
昨日の試験は難しくなかったです。
Yesterday's test was not difficult.
彼は速く走ります。
He runs fast.
昨日、新しい靴を買った。
Yesterday, I bought new shoes.
私の犬は大きい。
My dog is big.
昨日の試験は難しかった。
Yesterday's test was difficult.
この料理は辛くない。
This dish is not spicy.
昨日の試験は難しくなかった。
Yesterday's test was not difficult.
彼は速く走る。
He runs fast.
Example sentences
昨日は寒くなかったですが、今日は暖かいです。
It was not cold yesterday, but it is warm today.
先週買った大きい箱は重くなかったけれど、今は軽いです。
The large box I bought last week was not heavy, but it is light now.
この新しい店の料理はおいしくないですが、昨日食べたケーキは甘