JLPT N5 · Adjectives and comparing · 25 of 60

い-adjectives: 高い and 高くない

高い・高くない takai, takaku nai い-adjective conjugation

An い-adjective changes its own ending: 高い (expensive) becomes 高くない (not expensive). In English the adjective stays the same and "be" changes.

Level: JLPT N5, beginner
Type: Adjectives and comparing
English links: be + not, adjectives, negatives

What it means

い-adjectives end in い: 高い, 安い, 寒い, 難しい. They conjugate, which means the ending changes to show negative or past, just like a verb. For the negative, drop the last い and add くない: 高い becomes 高くない.

For polite speech, add です: 高くないです. You will also hear and read 高くありません, which is a little more formal. Both mean "is not expensive". One word breaks the rule: いい (good) becomes よくない, never いくない, because the old form of いい is よい.

Watch out for a few words that end in い but are な-adjectives: きれい (clean, pretty), きらい (dislike) and 有名 (famous) in its reading ゆうめい. They take ではありません, not くない. Learners at every level make this slip, so do not feel bad when you do.

How to build it

Pattern	How it works
高い → 高いです takai → takai desu	Positive. Add です to be polite.
高い → 高くないです / 高くありません takai → takaku nai desu / takaku arimasen	Negative. Drop い, add くない. The second form is a little more formal.
いい → よくないです ii → yoku nai desu	The one irregular い-adjective. Never いくない.
あまり + 高くないです amari + takaku nai desu	あまり with a negative means "not very".

Examples

このかばんは高くないです。 kono kaban wa takaku nai desu. This bag is not expensive.
今日はあまり寒くないです。 kyou wa amari samuku nai desu. It is not very cold today.
このテストは難しくありません。 kono tesuto wa muzukashiku arimasen. This test is not difficult.
駅は遠くないです。 eki wa tooku nai desu. The station is not far.
天気はあまりよくないです。 tenki wa amari yoku nai desu. The weather is not very good.

How English says it

English adjectives never change for the negative. The verb "be" takes "not": "The bag is not expensive", or in speech, "The bag isn't expensive". The word "expensive" stays exactly the same.

あまり～ない matches "not very" or "not really": "It is not very cold". English can also say "It isn't that cold" in speech.

Why it can make English hard

In Japanese the negative lives inside the adjective. In English it lives on "be". Students who feel 忙しくない as one verb-like word may reach for "don't", the negative they know from verbs.
ない sounds like "no", so some students write "no" where English needs "not".
Students may also leave out "be" completely, because 高くないです has no word for it.

Mistakes you will hear

I don't busy today. I am not busy today. 忙しくない behaves like a verb, so the student uses the verb negative "don't".
The test is no difficult. The test is not difficult. ない sounds like "no". English needs "not" after "be".
This bag not expensive. This bag is not expensive. The "be" goes missing because 高くないです has no word for it.

In the classroom

Make two columns on the board: "is" and "isn't". Read out Japanese adjectives, positive or negative, and students say the English sentence. Point at the column so they see the change is on "be", not on the adjective.
Drill "I'm not" against "I don't" with quick pairs: "I'm not hungry" / "I don't eat breakfast". Adjective with "am not", verb with "don't".
Use real things in the room. "Is the window open?" "Is the bag heavy?" Students answer "No, it isn't" in full.

Practice

Try each one, then open it to check.

1. Make it negative: 寒いです。

Answer: 寒くないです。 (or 寒くありません。)

Drop い, add くない.
2. Make it negative: いいです。

Answer: よくないです。

いい is irregular. Its negative comes from the old form よい.
3. Make it negative: きれいです。

Answer: きれいではありません。 (or きれいじゃないです。)

きれい ends in い but is a な-adjective, so it takes ではありません.
4. A student writes "I don't hungry." Fix it.

Answer: I am not hungry.

"Hungry" is an adjective, so the negative goes on "be".