Translation guide
A guide to understanding and using i-adjectives in Japanese, which are adjectives that end in い and conjugate for tense and polarity.
The learner wants to know what an i-adjective is and how to use it in its basic form.
An i-adjective is a Japanese adjective that ends in い in its dictionary form. It can directly modify a noun or end a sentence. Examples: 高い (takai, 'high/expensive'), 楽しい (tanoshii, 'fun').
This book is expensive.
I watched a fun movie.
The learner wants to express the negative form of an i-adjective.
Replace the final い with くない to make the negative form. This is the standard negative for i-adjectives.
This book is not expensive.
It's not cold today.
The learner wants to express the past tense of an i-adjective.
Replace the final い with かった to make the past tense. This is the standard past form for i-adjectives.
It was hot yesterday.
That movie was interesting.
The learner wants to express the negative past tense of an i-adjective.
Replace the final い with くなかった to make the negative past tense. This is the standard negative past form for i-adjectives.
It was not hot yesterday.
That movie was not interesting.
The learner wants to connect i-adjectives or use them in compound sentences.
Replace the final い with くて to make the te-form. This is used to connect adjectives or clauses.
This room is spacious and bright.
The price was high, so I couldn't buy it.
The learner wants to use an i-adjective as an adverb.
Replace the final い with く to make the adverbial form. This modifies a verb.
Run quickly.
Well done. (Note: いい 'good' becomes よく)
The learner wants to use i-adjectives in polite speech.
Add です after the i-adjective to make it polite. The adjective itself does not change. For negative, use くないです or くありません (more formal).
This book is expensive. (polite)
It is not expensive. (polite)
It is not expensive. (more formal)
The learner wants to use an i-adjective to modify a noun.
Place the i-adjective directly before the noun. The adjective keeps its dictionary form.
a high mountain
I-adjectives end in い and conjugate directly. Na-adjectives require な when modifying nouns and use だ/です for endings. Some adjectives like きれい (pretty) end in い but are na-adjectives because the い is part of the kanji reading, not a suffix.
a pretty flower (na-adjective, not i-adjective)
The adjective いい (good) is irregular. Its conjugations use よい as the base: よくない (negative), よかった (past), よくて (te-form).
good weather → was good