Japanese grammar
What does ～さ (nominalizing adjectives) mean? Japanese grammar N4
～さ (nominalizing adjectives) means the degree of ~, the ~ness (nominalizes adjectives).
| Level (estimated, JLPT framework) | N4 |
|---|---|
| Structure | Aい (drop い) + さ Aな + さ |
| Romaji | ~ sa |
| Meaning | the degree of ~, the ~ness (nominalizes adjectives) |
Forming it
| Exception | いい → よさ (not いさ) |
|---|---|
| i-adjective | Aい (drop い) + さ — 高い → 高さ・長い → 長さ・大きい → 大きさ |
| na-adjective | Aな (drop な) + さ — 便利な → 便利さ・静かな → 静かさ |
How to use it
Turning an adjective into a noun expressing an objectively measurable DEGREE.
- さ turns an adjective into a NOUN expressing a MEASURABLE, OBJECTIVE degree: 高い (tall/high) → 高さ (height), 長い (long) → 長さ (length), 重い (heavy) → 重さ (weight).
- Because it's objective, さ often pairs with numbers and measurement questions: 「この山の高さは三千メートルです」(the height of this mountain is 3,000 meters). This sentence CANNOT be replaced with 高み.
- This is a PRODUCTIVE suffix — it can attach to almost any adjective, including na-adjectives: 便利さ (level of convenience), 大切さ (level of importance). If unsure whether to choose さ or み, choosing さ is almost always safe.
- Note the exception いい → よさ (not いさ), like every other conjugation of いい (よくない・よかった). This is a common trap.
Examples
この山の高さは三千メートルです。
The height of this mountain is 3,000 meters.
この荷物の重さを教えてください。
Please tell me the weight of this luggage.
この機械のよさが分かりますか。
Do you understand the merits of this machine?
Keep in mind
- Commonly seen measurement words: 高さ・長さ・広さ・重さ・大きさ・深さ・速さ — worth memorizing as a whole group.
- さ is emotionally neutral — it only describes degree.
Common mistakes
-
Wrongこの山のいさは三千メートルです。
This mountain is three thousand meters tall.
Correctこの山の高さは三千メートルです。
Wrong adjective stem; and if it's いい, it must change to よさ — the form いさ never exists.
-
Wrongこの山の高みは三千メートルです。
This mountain's height is three thousand meters.
Correctこの山の高さは三千メートルです。
OBJECTIVE measurements use さ. み carries a subjective feeling and doesn't pair with a measurement number.
Exam tips
- Trap いい → よさ (not いさ) — the exam asks this often.
- If there's a MEASUREMENT NUMBER (メートル・キロ) → choose さ, not み.