Japanese - Adjectives
Japanese adjectives (形容詞 - keiyōshi) are a fascinating and relatively straightforward part of speech. The crucial element to understand is that there are two distinct types of adjectives, and they behave like different parts of speech—one conjugates like a verb, and the other behaves like a noun.
The two groups are: I-Adjectives and Na-Adjectives.
1. I-Adjectives (い形容詞 - i-keiyōshi)
These adjectives are the true adjectives of the Japanese language. They are called I-adjectives because they always end in the Hiragana character い (i) in their dictionary/plain form (e.g., おおきい - ōkii - big, さむい - samui - cold).
A. Core Characteristics
- Conjugate: I-Adjectives conjugate for tense (past/non-past) and polarity (affirmative/negative).
- Directly Modify Nouns: They can be placed directly before the noun they modify without any particle (e.g., おおきい いぬ - ōkii inu - a big dog).
- Can End a Sentence: They can directly end a sentence in the Plain Form (e.g., あの いぬは おおきい - That dog is big).
B. Conjugation Table for I-Adjectives
The い ending is always replaced or dropped when conjugating.
| Function | Suffix | おおきい (ōkii - big) | さむい (samui - cold) |
|---|---|---|---|
| Affirmative Present/Future (Plain) | い | おおきい | さむい |
| Negative Present/Future (Plain) | くない | おおきくない | さむくない |
| Affirmative Past (Plain) | かった | おおきかった | さむかった |
| Negative Past (Plain) | くなかった | おおきくなかった | さむくなかった |
| Connecting Form ("and") | くて | おおきくて かっこいい (big and cool) | さむくて いやだ (cold and unpleasant) |
Exception: いい (Good)
The adjective いい (ii - good) is an irregular I-adjective. While its present form is いい, all other conjugations revert to its older stem: よ (yo).
- Negative: よくない (yokunai)
- Past: よかった (yokatta)
2. Na-Adjectives (な形容詞 - na-keiyōshi)
These adjectives are sometimes referred to as adjectival nouns because, in their base form, they function exactly like nouns. They do not end in い (though a few do, which must be memorized as exceptions).
A. Core Characteristics
- Do Not Conjugate: The base adjective itself never changes; it uses the copula (です/だ) for tense and the noun negation structure (ではない) for negation.
- Use な to Modify Nouns: To modify a noun, the particle な must be inserted between the adjective and the noun (e.g., しずか\underline{な} へや - shizuka na heya - a quiet room).
- Use だ/です to End a Sentence: They require the copula to end a sentence (e.g., あのへやはしずか\underline{だ} - That room is quiet).
B. Conjugation Table for Na-Adjectives
Na-adjectives use the same endings as nouns to express tense and politeness.
| Function | Suffix | しずか (shizuka - quiet) | げんき (genki - healthy/lively) |
|---|---|---|---|
| Affirmative Present/Future (Plain) | だ | しずか\underline{だ} | げんき\underline{だ} |
| Negative Present/Future (Plain) | ではない (じゃない) | しずか\underline{ではない} | げんき\underline{ではない} |
| Affirmative Past (Plain) | だった | しずか\underline{だった} | げんき\underline{だった} |
| Negative Past (Plain) | ではなかった | しずか\underline{ではなかった} | げんき\underline{ではなかった} |
| Connecting Form ("and") | で | しずか\underline{で} きれい (quiet and pretty) | げんき\underline{で} いい (healthy and good) |
Comparison Summary
The key difference lies in how they connect to and modify nouns:
| Characteristic | I-Adjective | Na-Adjective |
|---|---|---|
| Ending | Always ends in い | Does not end in い (usually) |
| To Modify a Noun | Placed directly before the noun | Requires the particle な |
| To End a Sentence | Conjugates itself to express tense | Requires the copula (です/だ) |
| Example | あつい日 (atsui hi - a hot day) | べんり\underline{な}場所 (benri na basho - a convenient place) |