The Rebel いい — The Only Irregular Adjective

In the previous article, we learned the い-adjective conjugation formula: drop い, add くない/かった/くなかった. But one word refuses to play by the rules — いい (good).

Try it: いい → いい + くない → くない? — That makes no sense at all.

The True Identity of いい: よい

いい is actually a casual contraction of よい. In everyday speech, everyone says いい, but the moment conjugation is needed, よい steps in.

The conjugation follows standard い-adjective rules — just applied to よい instead of いい:

Only the "affirmative present" uses いい. All three other forms switch to よい conjugations. This is the only special conjugation you need to memorize at N5.

Say it out loud:

• いいです
• よくないです
• よかったです
• よくなかったです

あんまり + Negative: "Not very..."

Now that you know negative forms, you can unlock a super common daily expression: あんまり〜ない (not very...).

あんまり is an adverb meaning "not very," but it must be paired with a negative form:

あんまり always requires a negative! You cannot say あんまりいいです — that doesn't work in Japanese.

The Universal Complaint Sentence

With あんまり + よくない, you can grumble about anything:

給料はあんまりよくないです。 → The salary isn't very good.

天気はあんまりよくなかったです。 → The weather wasn't very good.

あんまりおいしくないです。 → It's not very tasty.

たいへん / とても: "Very..."

The opposite of あんまり: to say "very," use たいへん or とても, paired with affirmative forms:

Practical Dialogue: How Was the Trip?

A: 旅行はどうでしたか。 → How was the trip? B: とても楽しかったです。 → It was really fun!

If it wasn't great:

B: あんまり楽しくなかったです。 → It wasn't very fun.

Follow-up about weather:

A: 天気はよかったですか。 → Was the weather good? B: いいえ、あんまりよくなかったです。 → No, it wasn't very good.

Complete いい Conjugation Card

Memorize these four lines — they cover both exams and conversation:

いいです          → good
よくないです       → not good
よかったです       → was good
よくなかったです    → wasn't good

Paired with the three degree adverbs:

とても いいです          → very good
たいへん いいです        → very good (slightly formal)
あんまり よくないです    → not very good

Summary

• いい (good) uses its true form よい for conjugation: よくない / よかった / よくなかった
• Only "affirmative present" uses いいです — the other three all start with よ-
• あんまり = "not very," must pair with negative forms (〜くない / 〜ではありません)
• とても / たいへん = "very," pair with affirmative forms
• This is the only irregular い-adjective conjugation at N5

Self-Check

Q1. Say "not very tasty" in Japanese.

Q2. Conjugate いい into negative past and make a complete sentence.

Q3. Which sentence is correct? A. あんまりいいです。　B. あんまりよくないです。　C. あんまりよいです。