1A long, narrow mark or stripe on a surface (e.g., a stripe on cloth or a drawn line).
そのシャツには細い青い線が入っている。
That shirt has thin blue stripes.
画用紙に鉛筆でまっすぐな線を引いてください。
Please draw a straight line on the drawing paper with a pencil.
古い建物の壁に縦の線模様が残っている。
Vertical stripe patterns remain on the wall of the old building.
2A wire or line used for communication or electricity (e.g., telephone line, power line); also used for circuits/connections.
台風で電話線が切れて、電話がつながらなくなった。
The telephone line was cut by the typhoon, and the phone couldn't connect.
工事のために電線が一時的に取り外される。
The power lines will be temporarily removed for construction work.
インターネットは光ファイバー回線で接続されている。
The internet is connected via a fiber-optic line.
3A ray or beam of radiation (e.g., X-ray); refers to types of radiative rays or beams.
医者は骨折を確認するためにＸ線を撮った。
The doctor took an X-ray to check for a fracture.
放射線検査では高エネルギーの線が使われることがある。
High-energy rays are sometimes used in radiological examinations.
4A route or track such as a railway line; refers to a transit route, track, or lane (e.g., train line).
毎朝、山手線で会社に通っています。
I commute to work every morning on the Yamanote Line.
新しい地下鉄の線が来年開通する予定だ。
A new subway line is scheduled to open next year.
この港は多くの航路（線）と接続している。
This port connects to many shipping routes.
5The outline or contour of a shape; used for drawing outlines or indicating the form of something.
彫刻家はまず作品の線を紙に描いて確かめた。
The sculptor first drew the outline of the work on paper to check it.
このイラストは線が細かくてきれいだ。
This illustration has fine, beautiful line work.
6A level or threshold (e.g., a passing line); a boundary that separates grades, qualifications, or thresholds.
今度の試験の合格線は60点だと発表された。
It was announced that the passing line for this exam is 60 points.
チームは平均点で合格の線をぎりぎり超えた。
The team barely exceeded the passing threshold with their average score.
7A division or boundary; indicates a separating line or demarcation between areas, responsibilities, or categories.
会場には白い線で観客席と演技エリアを区切っていた。
The venue had the spectator area and performance area separated by a white line.
作業の線引きが不明確でトラブルが起きた。
Because the division of tasks was unclear, trouble occurred.
8A line of action, approach, policy, or principle; often used as in 'to proceed on the line of ~' or 'to take the approach of ~'.
会社はコスト削減の線で事業計画を見直した。
The company reviewed its business plan along the lines of cost reduction.
政府は中立の線を保ちながら調整を進めると言った。
The government said it would proceed with adjustments while maintaining a neutral stance.
9The impression or aura someone gives; used in expressions like 'has a strong presence' or 'delicate impression' (e.g., 太い線／細い線).
彼女は線が細くて、どこか儚げな雰囲気がある。
She has a delicate look and a somewhat fragile atmosphere.
あの俳優は線が太いので存在感がある役に向いている。
That actor has a strong presence, so he's suited to roles that require it.