Adjectives: い and な

Japanese adjectives come in two kinds, named after how they look when they describe a noun. The names are ugly, but the patterns are small and easy.

An い-adjective ends in い: 高い (tall/expensive), 新しい (new), おいしい (delicious), 大きい (big). Think of the い as part of the word, and the word as a full, self-contained predicate. It can close a sentence without だ:

It can also describe a noun directly, placed before it:

That is all there is to the basic use. In English you need "is" in the first case. In Japanese the adjective is the predicate. That's why い-adjectives behave like verbs: they change form to show negative and past, and they can close a sentence.

The recipe: drop the い and add くない (not), かった (was) or くなかった (was not).

Add です to be polite. You don't add です to make the past: 高かったです, not 高いでした.

The adjective いい (good) is irregular only in that its stem is よ. It conjugates as if it were よい:

The same happens with かっこいい → かっこよくない. Anything ending in いい does it.

A な-adjective (also called a na-adjective or adjectival noun) is a noun-like word that describes things: 静か (quiet), きれい (pretty, clean), 有名 (famous), 元気 (healthy, energetic). It does not end in い (with a few exceptions, like きれい and 嫌い).

Because it is noun-like, it behaves like a noun when it closes a sentence: you put だ or です after it.

When it describes a noun it takes な:

That's where the name comes from. And it conjugates exactly like a noun + だ:

To describe how something is done, change the adjective:

• い-adjective: change い to く (早い → 早く, 安い → 安く)
• な-adjective: change な to に (静か → 静かに, きれい → きれいに)

The same く/に form also appears with なる ("become") and する ("make into"):

To say "tall and handsome" or "cheap and delicious", change the adjective's ending:

• い-adjective: い → くて (安くておいしい: cheap and delicious)
• な-adjective: → で (静かで便利: quiet and convenient)

This is the "connecting" form. It's the same idea as the て-form for verbs, which we'll see soon.

Two useful endings:

• 〜すぎる — "too much": 高すぎる (too expensive), 静かすぎる (too quiet).
• とても / すごく / かなり — "very".

Stack adjectives in front of nouns, and join them at the end with くて or で.

A review in the past tense with negatives:

• い-adjectives end in い, close a sentence by themselves, and conjugate (くない, かった, くなかった).
• な-adjectives are noun-like: だ/です to close, な to describe a noun.
• いい conjugates from よい: よくない, よかった.
• く and に turn them into adverbs; くて and で join them.
• Don't add だ to an い-adjective.