Meaning
無 means nothing, absence, or lack — and it punches above its weight. Few kanji generate as many useful compounds. Put 無 in front of almost any noun, and you get its opposite: 無料 (free), 無理 (impossible), 無限 (infinite). Think of it as Japanese's "un-" or "non-" prefix.
The origin is surprisingly vivid. 無 began as a pictograph in ancient Chinese script depicting a person dancing with decorative tassels or feathers in both hands. Over time, the image was borrowed phonetically to express the abstract idea of nothingness — sound without meaning. That kind of semantic drift is common in the history of Chinese characters, even if the logic seems odd at first.
In Zen Buddhism, 無 takes on special weight. The concept of mu (無) — nothingness, no-mind — sits at the center of Zen koans and meditation practice. For many Japanese, 無 isn't just a grammar prefix; it carries centuries of philosophical history behind it.
Structurally, 無 has 12 strokes and is taught in Grade 4 of Japanese elementary school. Its radical is 火 (fire), visible as four dots (灬) along the bottom. The fire radical is there for classification purposes only — don't read any meaning into it.
Readings
On'yomi (音読み) — Chinese-derived readings
無 has two on'yomi readings: ム (mu) and ブ (bu). You'll encounter ム far more often — it appears in the vast majority of compounds, especially those with a negating prefix meaning.
ム (mu) — The primary reading. Nearly all 無 compounds you meet day-to-day use this.
- 無理 (muri) — impossible, unreasonable, overdoing it
- 無料 (muryō) — free of charge, no cost
- 無限 (mugen) — infinite, limitless, endless
- 無敵 (muteki) — invincible, unrivaled
ブ (bu) — A smaller set of words, often with a stronger negative or social nuance. These tend to combine with words of Chinese origin.
- 無礼 (burei) — rudeness, impoliteness, disrespect
- 無事 (buji) — safety, without incident, peace
Kun'yomi (訓読み) — Native Japanese readings
The kun'yomi is な.い (nai), connecting 無 to the native Japanese adjective meaning "there is not" or "does not exist." The dot in な.い marks where the kanji ends and the grammatical suffix (okurigana) begins.
- 無い (nai) — not exist, there is no, lacking
- 無くなる (nakunaru) — to disappear, to run out, to pass away
- 無くす (nakusu) — to lose something, to get rid of
Common Words & Compounds
無 is one of Japanese's most productive prefixes. Here are key compounds, grouped by theme.
Everyday & Practical
- 無料 (muryō) — free of charge; you'll see this on apps, shops, and websites constantly
- 無駄 (muda) — wasteful, useless, pointless; very common in casual speech
- 無理 (muri) — impossible, unreasonable; also a polite way to say "I can't" without being blunt
- 無事 (buji) — safe and sound, without incident; what you say when relief washes over you
Character & Behavior
- 無礼 (burei) — rudeness, impertinence; the formal word for impolite behavior
- 無責任 (musekinin) — irresponsibility, recklessness
- 無能 (munō) — incompetence, inability
- 無言 (mugon) — silence, wordlessness; without speaking
Abstract & Academic
- 無限 (mugen) — infinity, limitlessness; used in math, physics, and philosophy
- 無意識 (muishiki) — unconscious, subconscious; a psychology term
- 無関係 (mukankei) — unrelated, irrelevant, no connection
- 無効 (mukō) — invalid, null and void; standard in legal and official contexts
Other Notable Compounds
- 有無 (umu) — existence or non-existence; whether or not something is present
- 無視 (mushi) — to ignore, to disregard, to overlook
Example Sentences
このサービスは無料です。
Kono sābisu wa muryō desu.
This service is free of charge.
そんな無駄なことはやめてください。
Sonna muda na koto wa yamete kudasai.
Please stop doing such wasteful things.
無理しないで、ゆっくり休んでください。
Muri shinaide, yukkuri yasunde kudasai.
Don't push yourself too hard — please get plenty of rest.
家族が無事で本当によかった。
Kazoku ga buji de hontō ni yokatta.
I am truly relieved that my family is safe and sound.
この契約は無効だと判断されました。
Kono keiyaku wa mukō da to handan saremashita.
This contract was determined to be invalid.
彼は私の意見を無視した。
Kare wa watashi no iken wo mushi shita.
He ignored my opinion.
無責任な発言は許されない。
Musekinin na hatsugen wa yurusarenai.
Irresponsible statements cannot be forgiven.
宇宙は無限に広がっているように見える。
Uchū wa mugen ni hirogatte iru yō ni mieru.
The universe appears to expand infinitely.
Memory Tip
Picture 無 as a dance of emptiness. Its ancient origin was a person dancing with arms outstretched, holding decorative feathers — yet the space between those hands holds nothing. A performer spinning on stage, arms wide open, and at the center of that graceful spin: a void. That empty center is mu.
Whenever you see 無 in a word, something has been subtracted, removed, or was never there to begin with. The four dots at the bottom (the fire radical 灬) can remind you of sparks that have burned out — once there was fire, now there is nothing.