Meaning
幽 gathers its meanings around what is hidden, barely perceptible, or remote from the ordinary world: faint, dim, quiet, secluded, mysterious, deep. Think of light barely filtering through a dense forest canopy, or the stillness of a mountain valley no road has reached.
Structurally, 幽 is built from two instances of 幺 — an ancient pictograph of a small, twisted skein of thread — stacked above 山 (mountain). The image: wispy threads of mist curling above distant peaks, so faint they almost vanish before you can name them. That visual gives the kanji its core meaning: something barely perceptible, tucked away from the world.
Classical Chinese and Japanese literature reaches for 幽 again and again in aesthetic and philosophical writing. It is the central term in 幽玄, the Noh theater ideal of profound, ineffable beauty — the kind that lies beneath the surface of things rather than announcing itself. This aesthetic prizes restraint, suggestion, and the mystery of partial revelation. 幽 is more than a dictionary entry here. It names a specifically Japanese — and broadly East Asian — way of feeling about beauty, nature, and the spirit world.
幽 has 9 strokes and belongs to the 幺 radical (radical number 52). It appears in the Jōyō list at the supplementary high-school level — a sign of its literary rather than everyday register.
Readings
On'yomi (音読み) — Chinese-derived readings
幽 has one on'yomi: ユウ (yū), drawn from Middle Chinese pronunciation. It appears almost exclusively in compound words (熟語, jukugo), across both classical literature and modern vocabulary — particularly words touching the supernatural, the aesthetically remote, and physical or spiritual seclusion.
- 幽霊 (yūrei) — ghost, apparition; the most widely known compound, central to Japanese folklore and horror
- 幽玄 (yūgen) — profound, mysterious beauty; a foundational concept in Noh theater and classical Japanese arts
- 幽閉 (yūhei) — confinement, house arrest; literally, someone sealed away and hidden from the world
- 幽冥 (yūmei) — the realm of darkness, the world of the dead; found in Buddhist and Shinto texts
- 幽谷 (yūkoku) — deep, secluded valley; common in classical nature poetry
Kun'yomi (訓読み) — Native Japanese readings
The kun'yomi is かすか (kasuka): "faint," "dim," "slight." Most learners find this the easier entry point — it describes familiar sensory experience: a candle guttering in a draft, a voice calling from across a field, the tremor before an earthquake. It appears in both literary prose and everyday speech.
- 幽な声 (kasuka na koe) — a faint voice
- 幽な光 (kasuka na hikari) — a dim, faint light
- 幽に聞こえる (kasuka ni kikoeru) — to barely catch a sound
Older dictionaries also list くら(い) (kurai, "dark" or "gloomy"), but this reading is essentially extinct in modern Japanese, confined to Heian and Kamakura-period texts.
Common Words & Compounds
幽 clusters into three territories: the supernatural, the aesthetic, and the physically secluded. Knowing which territory a compound belongs to usually resolves the meaning on the spot.
Supernatural & Spiritual
- 幽霊 (yūrei) — ghost, spirit of the dead; omnipresent in Japanese culture, from folklore to J-horror films
- 幽冥 (yūmei) — the underworld; appears in Buddhist texts and classical poetry
- 幽界 (yūkai) — the spirit world, the afterlife; used in Shinto and folkloric contexts
- 幽明 (yūmei) — the boundary between the living and the dead (literary; note: same reading as 幽冥 but written with different kanji)
Aesthetic & Philosophical
- 幽玄 (yūgen) — subtle, profound beauty; the single most important compound for understanding 幽 as a cultural concept
- 幽雅 (yūga) — quietly elegant, tranquil in character
- 幽遠 (yūen) — profoundly remote; used in literary descriptions of landscape or emotion
- 幽邃 (yūsui) — deep and secluded; found in classical poetry about mountain scenery
Physical Seclusion & Confinement
- 幽閉 (yūhei) — confinement, house arrest; appears in historical and political contexts
- 幽囚 (yūshū) — captivity, imprisonment; formal and literary register
- 幽谷 (yūkoku) — deep, secluded valley; frequent in haiku and classical nature writing
- 幽境 (yūkyō) — a hidden place removed from the noise of the world
Example Sentences
夜の森に幽な光が見えた。
Yoru no mori ni kasuka na hikari ga mieta.
— A faint light was visible in the night forest.
幽霊が出ると噂のある古い屋敷に近づいた。
Yūrei ga deru to uwasa no aru furui yashiki ni chikazuita.
— We approached the old mansion rumored to be haunted.
能の舞台では幽玄の美が表現される。
Nō no butai de wa yūgen no bi ga hyōgen sareru.
— On the Noh stage, the beauty of yūgen is expressed.
彼女は城の塔に幽閉されていた。
Kanojo wa shiro no tō ni yūhei sarete ita.
— She was confined in the tower of the castle.
幽な足音が廊下の奥から聞こえてきた。
Kasuka na ashioto ga rōka no oku kara kikoete kita.
— Faint footsteps could be heard from the far end of the corridor.
この詩には幽遠な情景が詠まれている。
Kono shi ni wa yūen na jōkei ga yomarete iru.
This poem depicts a scene of deep, distant remoteness.
山の奥に幽谷が静かに広がっていた。
Yama no oku ni yūkoku ga shizuka ni hirogatte ita.
— A deep, secluded valley spread out quietly in the heart of the mountains.
彼の声は電話の向こうで幽に震えていた。
Kare no koe wa denwa no mukō de kasuka ni furuete ita.
— His voice was trembling faintly on the other end of the phone.
幽雅な庭園で一人茶を楽しんだ。
Yūga na teien de hitori cha o tanoshinda.
— I enjoyed tea alone in the quietly elegant garden.
古典文学において、幽明の境は人と霊が交わる場所だ。
Koten bungaku ni oite, yūmei no sakai wa hito to rei ga majiwaru basho da.
In classical literature, the boundary between this world and the next is where the living and spirits meet.
Memory Tip
Picture two wispy threads (幺幺) of morning mist drifting above a mountain (山) at dawn. The mist is so faint you can barely name it before it's gone — blink and it vanishes. That is 幽 (yū, kasuka): barely there, half-hidden, mysterious. The on'yomi yū even sounds right: soft, drawn-out, fading into silence. Spot those two small loops perched above the mountain base and think: quietly hidden from the world. It also explains 幽霊 (ghost): a ghost is exactly that kind of presence — flickering at the edge of perception, never quite solid enough to grasp.