Meaning
弦 (ゲン / つる) carries meanings across three distinct but interconnected domains: archery, music, and mathematics. At its most elemental, 弦 refers to a bowstring — the taut cord stretched across the curved frame of a bow (弓) that stores and releases energy to propel an arrow. That primal image of tension and release runs through every use of this character.
From the bowstring, the meaning extended naturally to the strings of musical instruments. Strings on a koto (琴), shamisen (三味線), biwa (琵琶), or in modern contexts a violin, cello, or guitar — all are referred to using 弦 or compounds built upon it. The physical similarity between a stretched bowstring and a taut instrument string made this semantic extension natural in classical Japanese and Chinese writing.
In geometry and trigonometry, 弦 means a chord — the straight line segment connecting two points on the circumference of a circle. This mathematical usage gave rise to 正弦 (sine) and 余弦 (cosine), both essential in physics, engineering, and advanced mathematics. In astronomy, 弦 appears in 上弦 (first quarter moon, waxing) and 下弦 (last quarter moon, waning) — phases in which the illuminated arc of the moon resembles the arc of a bow drawn taut.
Structurally, 弦 is composed of the radical 弓 (bow) on the left and 玄 (dark, mysterious; phonetic element) on the right. Together they evoke a dark, taut cord stretched tightly across a curved bow. With 8 strokes and Jōyō status at the high school level (grade 8), 弦 is a key target for JLPT N1 preparation. Its breadth of meaning — connecting archery, music, geometry, and astronomy through the single image of a vibrating string — makes it one of the more rewarding kanji to master at the advanced level.
Readings
On'yomi (音読み) — Chinese-derived readings
The on'yomi reading ゲン (GEN) is used in nearly all compound words and derives from the classical Chinese pronunciation xián. Musical, mathematical, and astronomical vocabulary all draw on this reading, making it dominant in formal, academic, and literary contexts. Encountering 弦 embedded in a longer compound, ゲン is almost always the correct choice.
- 弦楽 (gengaku) — string music; music performed by or written for string instruments
- 弦楽器 (gengakki) — string instrument (violin, koto, guitar, and so on)
- 管弦楽 (kangengaku) — orchestral music; the combination of wind instruments (管) and string instruments (弦楽)
- 正弦 (seigen) — sine; the fundamental trigonometric function
- 上弦 (jōgen) — first quarter moon; the waxing crescent phase
- 下弦 (kagen) — last quarter moon; the waning crescent phase
Kun'yomi (訓読み) — Native Japanese readings
The kun'yomi reading つる (tsuru) is the native Japanese word for a physical string, cord, or wire stretched taut. Use it when referring to a specific, tangible string — the actual bowstring of a bow or an individual string on a traditional Japanese instrument. Notably, つる also refers to the temple arms (earpiece hooks) of eyeglasses (眼鏡の弦), since they curve around the ear recalling the arc of a bowstring. This reading tends to appear in concrete, everyday speech rather than formal academic usage.
- 弓弦 (yumizuru) — bowstring; the taut cord of an archer's bow
- 琴の弦 (koto no tsuru) — koto string; an individual string on the Japanese zither
- 眼鏡の弦 (megane no tsuru) — the temple arm of eyeglasses; the piece that hooks over the ear
Common Words & Compounds
弦 appears across music, astronomy, and mathematics. Below are key compounds grouped by field.
Music and String Instruments:
- 弦楽 (gengaku) — string music
- 弦楽器 (gengakki) — string instrument
- 弦楽四重奏 (gengaku shijūsō) — string quartet; an ensemble of four string players
- 管弦楽 (kangengaku) — orchestral music; wind and string instruments together
- 管弦楽団 (kangengakudan) — orchestra; symphony orchestra
- 弓弦 (yumizuru) — bowstring; the taut cord of an archer's bow
Astronomy:
- 上弦 (jōgen) — first quarter moon (waxing); the arc faces upward like a bow held up
- 下弦 (kagen) — last quarter moon (waning); the arc faces downward like an inverted bow
- 弦月 (gengetsu) — crescent moon; half-moon shape resembling the arc of a bowed string
Mathematics (Trigonometry and Geometry):
- 正弦 (seigen) — sine; one of the fundamental trigonometric functions
- 余弦 (yogen) — cosine; the complementary trigonometric function to sine
Everyday Use:
- 眼鏡の弦 (megane no tsuru) — temple arm of eyeglasses; the piece that curves around the ear
Example Sentences
ギターの弦が切れてしまったので、新しいものを買いに行った。
Gitā no gen ga kirete shimatta no de, atarashii mono o kai ni itta.
The guitar string broke, so I went to buy a replacement.
夜空に上弦の月が美しく輝いていた。
Yozora ni jōgen no tsuki ga utsukushiku kagayaite ita.
The first-quarter moon shone bright in the night sky.
数学の授業で正弦と余弦の公式を暗記した。
Sūgaku no jugyō de seigen to yogen no kōshiki o anki shita.
I memorized the sine and cosine formulas in math class.
管弦楽団の演奏を聴いて、感動して涙が出た。
Kangengakudan no ensō o kiite, kandō shite namida ga deta.
Listening to the orchestra perform moved me to tears.
弦楽四重奏のコンサートに友人と一緒に行った。
Gengaku shijūsō no konsāto ni yūjin to issho ni itta.
I went to a string quartet concert with a friend.
琴の弦を丁寧に調整する師匠の姿が印象的だった。
Koto no tsuru o teinei ni chōsei suru shishō no sugata ga inshōteki datta.
Watching my teacher carefully tune the koto strings left a strong impression on me.
弓の弦を最大限に引き、的に向かって矢を放った。
Yumi no tsuru o saidaigen ni hiki, mato ni mukatte ya o hanatta.
He drew the bowstring to its limit and released the arrow toward the target.
この弦楽器は、熟練した職人が一本一本の弦を手作業で張ったものだ。
Kono gengakki wa, jukuren shita shokunin ga ippon ippon no gen o tesagyō de hatta mono da.
This string instrument was strung by hand, one string at a time, by a skilled craftsman.
弦の振動の周波数が音の高低を決めるのだと、物理の先生が説明してくれた。
Gen no shindō no shūhasū ga oto no kōtei o kimeru no da to, butsuri no sensei ga setsumei shite kureta.
The physics teacher explained that a string's vibration frequency determines the pitch of the sound.
Memory Tip
Close your eyes and picture an archer at dusk in ancient Japan. In the left hand: a curved bow — 弓. Against the darkening sky, the bowstring is nearly invisible, a thin black cord humming with tension. That dark cord is 玄, the right half of 弦, a character that literally means dark or mysterious. Feel the bow creak as the string is drawn back; hear it sing when released. That singing cord — 弓 (bow) wrapped around 玄 (dark thread) — is 弦. Once that image is fixed, the rest follows: a vibrating string makes music, so 弦 names instrument strings. A taut string pulled between two points traces a straight line, so 弦 names the geometric chord. And the moon's glowing arc, curved like a bow in the night sky, takes its name from the same character. Every time 弓 appears on the left of a kanji, look for its string.