Two Types of Adjectives
Unlike English, Japanese has two completely different types of adjectives that conjugate differently:
- I-adjectives (い形容詞) - end in い, conjugate like verbs
- Na-adjectives (な形容詞) - need な before nouns, conjugate with だ
I-Adjectives (い形容詞)
Identification
Always end in い in dictionary form:
大きい (ookii) - big
小さい (chiisai) - small
高い (takai) - tall/expensive
安い (yasui) - cheap
美しい (utsukushii) - beautiful
Key Feature
Conjugate like verbs - change their ending directly:
大きい → 大きかった (was big)
大きい → 大きくない (not big)
大きい → 大きくて (big and...)
Using I-Adjectives
Before nouns (no particle needed):
大きい犬
ookii inu
"big dog"
高い車
takai kuruma
"expensive car"
As predicate (sentence ending):
この犬は大きい
kono inu wa ookii
"This dog is big"
その車は高い
sono kuruma wa takai
"That car is expensive"
Basic Conjugation
Present affirmative:
大きい (ookii) - is big
Past affirmative:
大きかった (ookikatta) - was big
Present negative:
大きくない (ookikunai) - is not big
大きくありません (ookiku arimasen) - is not big (polite)
Past negative:
大きくなかった (ookirunakatta) - was not big
大きくありませんでした (ookiku arimasendeshita) - was not big (polite)
Adverb Form
Drop い, add く:
早い (hayai) - early/fast
→ 早く (hayaku) - early/quickly
静かい? NO - 静か is na-adjective!
早く走る
hayaku hashiru
"run quickly"
早く来て
hayaku kite
"come early"
Na-Adjectives (な形容詞)
Identification
Don't end in い (usually). Need な before nouns:
静か (shizuka) - quiet
綺麗 (kirei) - beautiful/clean
便利 (benri) - convenient
好き (suki) - likeable
有名 (yuumei) - famous
Key Feature
Behave like nouns - need な to modify nouns, conjugate with だ/です:
静かな部屋 (with な before noun)
部屋は静かだ (with だ as predicate)
Using Na-Adjectives
Before nouns (need な):
静かな部屋
shizuka na heya
"quiet room"
綺麗な花
kirei na hana
"beautiful flower"
As predicate (with だ/です):
この部屋は静かだ
kono heya wa shizuka da
"This room is quiet"
その花は綺麗です
sono hana wa kirei desu
"That flower is beautiful"
Basic Conjugation
Present affirmative:
静かだ (shizuka da) - is quiet
静かです (shizuka desu) - is quiet (polite)
Past affirmative:
静かだった (shizuka datta) - was quiet
静かでした (shizuka deshita) - was quiet (polite)
Present negative:
静かじゃない (shizuka janai) - is not quiet
静かではありません (shizuka dewa arimasen) - is not quiet (polite)
Past negative:
静かじゃなかった (shizuka janakatta) - was not quiet
静かではありませんでした (shizuka dewa arimasendeshita) - was not quiet (polite)
Adverb Form
Add に:
静か (shizuka) - quiet
→ 静かに (shizuka ni) - quietly
綺麗 (kirei) - beautiful
→ 綺麗に (kirei ni) - beautifully
静かに話す
shizuka ni hanasu
"speak quietly"
Tricky Cases: いい
いい (ii) means "good" but conjugates irregularly using よ:
Present: いい (ii) / 良い (yoi) - good
Past: 良かった (yokatta) - was good
Negative: 良くない (yokunai) - not good
Adverb: 良く (yoku) - well
Don't say: いかった ❌
Say: 良かった ✓
Confusing Na-adjectives
Some na-adjectives end in い, confusing learners:
嫌い (kirai) - dislikeable → na-adjective
綺麗 (kirei) - beautiful → na-adjective
有名 (yuumei) - famous → na-adjective
How to tell:
- Most dictionary entries mark them as な形容詞
- They need な before nouns
- They use だ/です as predicate
嫌いな食べ物 (kirai na tabemono) - disliked food
綺麗な人 (kirei na hito) - beautiful person
Connecting Adjectives
I-adjectives: て-form
Drop い, add くて:
大きくて白い犬
ookikute shiroi inu
"a big and white dog"
この部屋は広くて明るい
"This room is spacious and bright"
Na-adjectives: で
Use で to connect:
静かで便利な場所
shizuka de benri na basho
"a quiet and convenient place"
彼女は親切で優しい
"She is kind and gentle"
Common I-Adjectives
大きい (ookii) - big
小さい (chiisai) - small
高い (takai) - tall/expensive
低い (hikui) - low/short
広い (hiroi) - spacious
狭い (semai) - narrow
新しい (atarashii) - new
古い (furui) - old
良い (yoi/ii) - good
悪い (warui) - bad
多い (ooi) - many
少ない (sukunai) - few
Common Na-Adjectives
静か (shizuka) - quiet
綺麗 (kirei) - beautiful/clean
便利 (benri) - convenient
不便 (fuben) - inconvenient
好き (suki) - likeable
嫌い (kirai) - dislikeable
有名 (yuumei) - famous
親切 (shinsetsu) - kind
元気 (genki) - energetic/healthy
簡単 (kantan) - simple/easy
Side-by-Side Comparison
| Feature | I-adjectives | Na-adjectives |
|---|---|---|
| Ending | い | Various (often kanji) |
| Before noun | 大きい犬 | 静かな犬 |
| As predicate | 大きい | 静かだ/です |
| Past | 大きかった | 静かだった |
| Negative | 大きくない | 静かじゃない |
| Adverb | 大きく | 静かに |
| Connect | 大きくて | 静かで |
Degrees of Intensity
Very / Quite
Use とても (totemo) or very casual すごく (sugoku):
とても大きい
totemo ookii
"very big"
すごく綺麗です
sugoku kirei desu
"super beautiful"
A Little
Use ちょっと (chotto) or 少し (sukoshi):
ちょっと高い
chotto takai
"a little expensive"
少し寒い
sukoshi samui
"a bit cold"
Too Much
Use すぎる (sugiru) - attach to stem:
I-adjectives: Drop い, add すぎる
高すぎる (takasugiru) - too expensive
大きすぎる (ookisugiru) - too big
Na-adjectives: Add すぎる directly
静かすぎる (shizukasugiru) - too quiet
便利すぎる (benrisugiru) - too convenient
Comparative Patterns
More than (より)
A は B より 形容詞
東京はロンドンより大きい
"Tokyo is bigger than London"
この部屋はあの部屋より静かです
"This room is quieter than that room"
Most (一番)
A は 一番 形容詞
富士山は一番高い
"Mt. Fuji is the tallest"
これが一番好きです
"I like this the most"
See: Comparisons
Adjectives as Nouns
I-adjectives: Drop い, add さ
高い (takai) → 高さ (takasa) - height
大きい (ookii) → 大きさ (ookisa) - size
Na-adjectives: Add さ
静か (shizuka) → 静かさ (shizukasa) - quietness
便利 (benri) → 便利さ (benrisa) - convenience
Common Mistakes
Mistake 1: Using い-adjective Pattern with Na-adjectives
Wrong: 綺麗い部屋 ❌
Right: 綺麗な部屋 ✓
Mistake 2: Forgetting な Before Nouns
Wrong: 静か部屋 ❌
Right: 静かな部屋 ✓
Mistake 3: Wrong Conjugation
Wrong: 大きいだった ❌
Right: 大きかった ✓
I-adjectives don't need だ/です for past.
Mistake 4: Mixing Politeness
Wrong: 大きいです → 大きかったです (past) ✓
Not: 大きいでした ❌
I-adjectives: adjective + です
Not: adjective + でした
Mistake 5: Wrong Adverb Formation
Wrong: 早いに ❌
Right: 早く ✓
I-adjectives use く, not に.
Special Cases
Colors
Most are na-adjectives, except three:
I-adjectives:
赤い (akai) - red
青い (aoi) - blue
黄色い (kiiroi) - yellow
Na-adjectives:
白 (shiro) - white → 白い服 (shiroi fuku)
黒 (kuro) - black → 黒い車 (kuroi kuruma)
茶色 (chairo) - brown → 茶色な目 (chairo na me)
Wait, 白い and 黒い are actually i-adjectives! They end in い and conjugate like i-adjectives.
Emotions/States
Often na-adjectives:
元気 (genki) - energetic → 元気な人
幸せ (shiawase) - happy → 幸せな時間
大変 (taihen) - tough/terrible → 大変な仕事
Politeness Levels
Casual (Plain)
大きい (i-adj) - big
静かだ (na-adj) - quiet
Polite
大きいです (i-adj) - big
静かです (na-adj) - quiet
Very Polite (Formal)
大きゅうございます (i-adj) - very rare, archaic
静かでございます (na-adj) - formal service language
Most situations need only plain or です form.
Practice Framework
Step 1: Identify Type
Does it end in い and conjugate? → I-adjective
Does it need な before nouns? → Na-adjective
Step 2: Choose Form
Before noun? → Add な for na-adjectives
End of sentence? → Conjugate appropriately
Step 3: Conjugate
I-adjectives: Change い ending
Na-adjectives: Use だ/です forms
Quick Reference Chart
I-adjective (大きい)
Present: 大きい
Past: 大きかった
Negative: 大きくない
Past Neg: 大きくなかった
Adverb: 大きく
Connect: 大きくて
Before noun: 大きい犬 (no particle)
Na-adjective (静か)
Present: 静かだ/です
Past: 静かだった/でした
Negative: 静かじゃない/ではありません
Past Neg: 静かじゃなかった/ではありませんでした
Adverb: 静かに
Connect: 静かで
Before noun: 静かな犬 (need な)
Key Takeaways
✓ Two types: I-adjectives (い) and Na-adjectives (な)
✓ I-adjectives conjugate directly, like verbs
✓ Na-adjectives need な before nouns, conjugate with だ/です
✓ Both can modify nouns or be predicates
✓ Some na-adjectives end in い (嫌い, 綺麗)
✓ Adverbs: I-adjectives use く, Na-adjectives use に
Understanding both adjective types is essential - they're used constantly in Japanese and follow completely different patterns.
Next: Noun Basics
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