How to say "circuit" in Japanese

• 回路かいろJLPT N1approx.Common
  nounCovers the electrical sense of 'circuit': a closed path for current, as in electronics or wiring. Use this when talking about circuits inside devices or on circuit boards.
  保護ほご回路かいろを飛とばしてしまおう。↗

  Let's bypass the protection circuit.
• 回線かいせんCommon
  nounCovers the telecommunications sense: a circuit or line connecting phones or networks. It also glosses simply as 'line', so this is the word for a connection or subscription line rather than electronic wiring.
  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.

Use 回路 for an electrical/electronic circuit, and 回線 for a circuit or line in the sense of a telecommunications connection; the choice depends on whether you mean wiring or a communication link.

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

• 回路かいろcircuit
• 回線かいせんcircuit
• サーキット(electric) circuit
• 道どうcircuit (administrative region of China)