回線|かいせんkaisen[0]heiban (flat)

1. nouncircuit; line
   この回線かいせんの細ほそさじゃ、動画どうがは見みられないよ。↗

   This connection is too slow for me to watch movies.

• Related回路かいろWrittenWritten, technical term for a loop that electric current flows through; also a cycle or loop (e.g. the Krebs cycle). 「回線」 is for communication, phone and network lines.
• RelatedサーキットNeutralLoanword with varied uses: an electric circuit, a racing track, or a tour of events. For communication lines, say 「回線」.
• Related経路けいろNeutralMeans a route or path, with a broad range: routes for travel, infection, information and more; not limited to communication.
• Related線せんNeutralGeneral word for a line or stripe, also used for lines such as telephone lines. When you mean a communication line specifically, use 「回線」.
• Related電線でんせんNeutralThe physical metal wire or cable that conducts electricity, e.g. overhead power lines. 「回線」 is the communication line as a system.
• Related電話線でんわせんNeutralThe physical cable used for landline phones. 「回線」 emphasizes the line for calls and communication, as in 「電話回線」.
• RelatedケーブルNeutralLoanword for a physical cable, e.g. 「LANケーブル」; also means a cable car. 「回線」 is the communication line.
• RelatedルートNeutralLoanword for a route or channel, e.g. 「販売ルート」; focuses on distribution channels. Does not refer to communication lines.
• Related電気回路でんきかいろWrittenWritten electrical-engineering term for a circuit that current flows through, limited to the circuit itself. 「回線」 refers to communication lines.
• Related電路でんろWrittenA rarer technical term for a path that electric current travels; everyday speech uses 「回路」. Does not refer to communication lines.
• Related電纜でんらんWrittenAn old-fashioned written word for cable, rarely used today; in everyday speech say 「ケーブル」.

Use 「回線」 for communication, telephone and network lines, as in 「光回線」. For electric circuits use 「回路」; for physical wires and cables use 「電線」 or 「ケーブル」; for routes and paths use 「経路」.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

1. 電信でんしんや電話でんわなど通信機器つうしんききを線せんで結むすんだ回路かいろ。