Negative Form of Japanese Adjectives

In English, you may simply use the word not to negate the meaning of an adjective. But in Japanese, it is done by modifying the suffix of the adjective.

Rules for Negative Form of Japanese Adjectives

• な-adjective: keep the stem of the adjective (without な), and add じゃない.
• い-adjective: keep the stem of the adjective, and change い to く, and add ない.
• Exception: いい (means good) becomes よくない

Notice that suffix ない means not in Japanese, and all negative forms effectively become い-adjectives as they end with ない.

Examples for な-adjectives:

• げんき → げんきじゃない (not healthy)
• すき → すきじゃない (dislike)
• しずか → しずかじゃない (not quiet)
• べんり → べんりじゃない (not convenient)

Examples for い-adjectives:

• おおきい → おおきくない (not big)
• あつい → あつくない (not hot)
• おもしるい → おもしるくない (not interesting)
• あかい → あかくない (not red)
• いい → よくない (not good)

You always use this plain form as a noun-modifier:

The polite form is used at the end of a sentence by adding です to the negative form, just like how you would do for the positive form.