Meaning
The kanji 線 primarily refers to a 'line,' 'thread,' 'stripe,' or 'wire.' It's a versatile character essential for describing anything elongated, continuous, or that functions as a boundary or connection. From literal straight lines we draw to abstract lines of thought or travel routes, 線 encompasses a wide range of linear concepts.
You can understand its origin by looking at its components. The left-hand radical is 糸, meaning 'thread' or 'silk.' This immediately provides the kanji's semantic core, linking it to thin, continuous filaments. Imagine a single strand of thread — it is, at its heart, a line.
The right-hand component is 泉, which means 'spring' or 'fountain.' While 泉 typically refers to a water source, here it mainly functions as a phonetic component, guiding the pronunciation to 'sen.' However, you can also metaphorically connect the continuous flow of water from a spring to the idea of an unbroken line. Thus, the visual shape of 線 cleverly combines the 'thread' (糸) with a phonetic element that subtly reinforces continuity, ultimately forming the concept of a 'line.'
Composed of 13 strokes, 線 is taught in the second grade of Japanese elementary schools. This places it at a relatively early stage in kanji education, yet its broad applications make it a crucial character for JLPT N3 learners and beyond.
Readings
On'yomi (音読み) — Chinese-derived readings
The primary on'yomi (Chinese-derived reading) for 線 is セン (sen). This is by far the most common reading, appearing in the vast majority of compound words. It carries the core meaning of 'line,' 'wire,' or 'route' in various contexts.
- 直線 (chokusen) — straight line
This compound combines 直 (straight) with 線 (line) to explicitly mean a 'straight line.' You'll encounter it in mathematics, drawing, and descriptive contexts.
- 路線 (rosen) — route, line (e.g., bus or train line)
Here, 路 means 'road' or 'route.' Thus, 路線 refers to a defined path or service line, commonly seen in bus, train, or airline routes.
- 電線 (densen) — electric wire
This compound joins 電 (electricity) with 線 (line/wire), creating the term for an 'electric wire' or 'power line.'
- 無線 (musen) — wireless
In this word, 無 means 'without.' So, 無線 means 'without a line' or 'wireless,' frequently referring to wireless communication like Wi-Fi or radio.
Kun'yomi (訓読み) — Native Japanese readings
The native Japanese reading for 線 is すじ (suji). While listed in dictionaries, this reading is considerably less common than its on'yomi. It typically appears in more specific, nuanced, or perhaps archaic contexts.
The reading すじ is often used when 線 implies a 'streak' or 'fiber' rather than a geometric line. You might also find it in expressions where the 'line' has a more organic or narrative quality.
- 細い線 (hosoi suji) — thin line, fine streak
While 細い線 is more common for a 'thin line' in general, 細い線 can be used when referring to a thin streak or fiber. This often implies a natural or subtle mark, such as a thin line of thread or a streak of dirt on a surface.
- 一条の線 (ichijō no suji) — a single line/streak
This expression, often found in literature, refers to a single, thin, or faint line or streak, like a beam of light through a crack or a faint trail. While 一条の線 is also valid, すじ here can emphasize the delicate or continuous flow of the line.
Common Words & Compounds
The kanji 線 combines with many other characters to form a rich vocabulary. Here are some common words and compounds, categorized by theme:
Spatial & Geometric Lines
- 曲線 (kyokusen) — curved line
The opposite of 直線, a 曲線 is any line that isn't straight, like an arc or a wave.
- 水平線 (suiheisen) — horizontal line, horizon
Combining 水 (water) and 平 (flat/level), this word refers to a flat, level line, most often the horizon where the sky meets the sea or land.
- 地平線 (chiheisen) — horizon
Similar to 水平線, 地平線 specifically refers to the line where the earth (地) meets the sky, particularly when discussing land-based horizons.
- 縦線 (jūsen) — vertical line
This term denotes a line oriented vertically, running from top to bottom.
Infrastructure & Communication
- 電車線 (denshasen) — tram line, train line
This term specifically refers to the line or route followed by electric trains or trams.
- 電話線 (denwasen) — telephone line
This is the physical wire or cable used for telephone communication.
- 有線 (yūsen) — wired, cable
The opposite of 無線, 有線 refers to communication or systems that rely on physical wires or cables.
- 回線 (kaisen) — circuit, line (e.g., internet line)
This refers to a communication circuit or line, like an internet connection or a telephone circuit.
Figurative & Abstract Lines
- 境界線 (kyōkaisen) — boundary line, demarcation line
This compound refers to a line that marks a boundary or division. It can be physical, like a country border, or abstract, such as the line between good and evil.
- 基準線 (kijunsen) — reference line, baseline
This is a line that serves as a standard or point of reference for measurement or comparison.
- 一線 (issen) — a line, a border, the front line
Often used figuratively, 一線 can mean 'a line of distinction,' 'the forefront,' or 'a boundary not to be crossed.'
- 最前線 (saizensen) — frontline, cutting edge
Meaning the very front line, it's typically used in military contexts or to describe the cutting edge of innovation or research.
- 最終線 (saishūsen) — final line, last resort
This refers to a final limit, a last resort, or a terminal line.
Example Sentences
紙に一本の線を引きました。
Kami ni ippon no sen wo hikimashita.
I drew a line on the paper.
電車の路線図を確認してください。
Densha no rosenzu wo kakunin shite kudasai.
Please check the train route map.
彼は直線的な考え方をします。
Kare wa chokusenteki na kangaekata wo shimasu.
He has a straightforward way of thinking.
電話線が切れて、インターネットが使えません。
Denwasen ga kirete, intānetto ga tsukaemasen.
The telephone line is cut, so I can't use the internet.
水平線に夕日が沈んでいきました。
Suiheisen ni yūhi ga shizunde ikimashita.
The setting sun sank below the horizon.
ここからあちらは境界線です。
Koko kara achira wa kyōkaisen desu.
From here to there is the boundary line.
目標達成のために、具体的な行動線を引く必要がある。
Mokuhyō tassei no tame ni, gutaiteki na kōdōsen wo hiku hitsuyō ga aru.
To achieve our goals, we need to map out a clear course of action (literally, 'action line').
国境には厳重な監視線が張られている。
Kokkyō ni wa genjū na kanshisen ga hararete iru.
A strict surveillance line is maintained along the border.
この製品は品質管理の基準線を満たしています。
Kono seihin wa hinshitsu kanri no kijunsen wo mitashite imasu.
This product meets the quality control baseline.
最新のテクノロジーは社会の最前線にあります。
Saishin no tekunorojī wa shakai no saizensen ni arimasu.
The latest technology is at the forefront of society.
Memory Tip
To remember 線, think of its components: 糸 (thread) and 泉 (spring/fountain). Imagine a thin, continuous line being spun from a spool of thread (糸). The continuous flow of water from a spring (泉) can help you recall the 'sen' sound, as 'sen' is part of the kanji's historical phonetic origins. So, a 'line' is a 'thread' flowing like a 'spring'.