い-Adjectives

Adjectives (形容詞, “keiyōshi”) play a crucial role in the Japanese language, helping to describe people, objects, feelings, and situations.

Firstly, let’s talk about this in English. We don’t simply use adjectives to add extra descriptions to nouns just for the sake of it, but they actually play a vital role in how we express ourselves in the language. Adjectives help convey specific details and characteristics, allowing us to communicate more clearly and effectively. They give us the power to paint a more vivid picture and to provide more nuance to our speech or writing.

For example, when we say “fast car,” we’re not just talking about a car, but a car with a particular characteristic—its speed. Similarly, when we describe a “big house,” we’re emphasizing the size of the house, which can evoke a sense of grandeur or spaciousness. In the case of “hard metal,” the adjective “hard” conveys the physical quality of the metal, distinguishing it from softer materials. Without adjectives, our language would be much more basic and less expressive. These descriptive words are essential for adding depth to our communication and making it more engaging and specific.

Now in Japanese, adjectives are categorized into い-adjectives (い形容詞, “ikeiyoshi”) and な-adjectives (な形容詞, “ikeiyoshi”). We will focus on い-adjectives, their conjugations, and how to use them in sentences.

Fundamentals

い-adjectives are a category of adjectives in the Japanese language that always end with the hiragana character い.

For example:

As seen in the examples above, all い-adjectives end in い.

Using Adjectives

When using い-adjectives in a sentence, they function similarly to English adjectives, appearing before the noun they describe. This is only specifically for い-adjectives and not the な-adjective.

For example:

大きい (ookii) – Big
大きい犬 (ookii inu) – Big dog

小さい (chiisai) – Small
小さい猫 (chiisai neko) – Small cat

高い (takai) – Expensive
高い車 (takai kuruma) – Expensive car

寒い (samui) – Cold
寒い日 (samui hi) – Cold day

Conjugation

In the Japanese language, you can do conjugations in adjectives to change the tense and politeness of the adjective.

Stem Form

First of all, you need to first be aware of the stem form before doing conjugates. The stem form is the part of the word that stays the same when you change the adjective tense.

Let’s look at an example with the word 寒い (samui, “cold”)

You can see that the part of the word that stays the same is “samu”, and the rest of the word changes. Hence when you conjugation, anything after “samu” will be the one changing.

Present Tense　(Dictionary Form)

When you present the adjective as it is without changing the tense, the adjective will be in present tense by default.

For example:

寒い (samui)

Present Negative　(〜くない)

To make an い-adjective negative, replace 〜い with 〜くない.

For example:

Casual
 寒くない (samuku nai, "not cold")

Polite
寒くないです (samukunai desu, "not cold")

Casual
寒かった (samukatta, "was cold")

Polite
寒かったです (samukatta desu, "was cold")

Past Negative　(〜くなかった)

To make an い-adjective negative in past tense, replace 〜い with 〜くなかった.

For example:

Casual
寒くなかった (samuku nakatta, was not cold)

Polite
寒くなかったです (samuku nakatta desu, "was not cold")

Other Grammar Structures

Listing multiple adjectives（〜くて）

To list multiple い-adjectives, replace 〜い with 〜くて.

For example:

彼は背が高くて、ハンサムです。
(Kare wa se ga takakute, hansamu desu.)
"He is tall and handsome."

その本は安くて、面白いです。
(Sono hon wa yasukute, omoshiroi desu.)
"That book is cheap and interesting."

Too Much (〜すぎる)

To say something is “too” (e.g., too big, too expensive), add すぎる after the い-adjective stem (remove い).

For example:

この映画は長すぎる。
(Kono eiga wa nagasugiru.) 
"This movie is too long."

その店は高すぎます。
(Sono mise wa takasugimasu.) 
"That shop is too expensive."

Becoming Something (くなる)

To express a change in state (e.g., becoming cold, getting better), replace 〜い with 〜くなる.

For example:

だんだん寒くなる。
(Dandan samukunaru.) → "It's gradually getting colder."

日本語が上手くなりました。
(Nihongo ga umaku narimashita.) → "My Japanese has improved."