(へいこう)

へいこう
noun / na-adjective
parallel
See also: 並行(へいこう) (parallel, concurrent)
1. parallel
Lines or surfaces that maintain equal distance and never intersect.
この(ふた)つの(せん)平行(へいこう)だ。
These two lines are parallel.
線路(せんろ)平行(へいこう)(はし)っている。
The railroad tracks run parallel to each other.
平行(へいこう)(ふた)つの(せん)はどこまで()ばしても(まじ)わらない。
Two parallel lines never intersect no matter how far they are extended.
2. simultaneous; concurrent
Doing multiple things at the same time.
仕事(しごと)勉強(べんきょう)平行(へいこう)して(すす)める。
To pursue work and studies simultaneously.
(ふた)つのプロジェクトを平行(へいこう)して(すす)めている。
We are working on two projects simultaneously.
(はな)()いは平行線(へいこうせん)のままで、なかなか結論(けつろん)()なかった。
The discussion remained at a stalemate, and no conclusion was reached.
平行線(へいこうせん) (parallel lines) is used figuratively to mean that two sides cannot reach agreement.

平行(へいこう) has both a geometric meaning (parallel lines) and a figurative meaning (doing things simultaneously).

GEOMETRIC SENSE:

  • 平行線(へいこうせん): parallel lines
  • 平行四辺形(へいこうしへんけい): parallelogram

FIGURATIVE SENSE:

  • 平行(へいこう)して(すす)める: to pursue simultaneously
  • 平行線(へいこうせん)をたどる: to remain at a stalemate (a discussion where two sides never meet, like parallel lines)

RELATED TERMS:

  • 垂直(すいちょく): perpendicular, vertical
  • 並行(へいこう): concurrent, simultaneous (the variant spelling preferred for the "simultaneous" meaning)

NOTE:
平行(へいこう) and 並行(へいこう) are homophones. 平行(へいこう) emphasizes the geometric sense; 並行(へいこう) is preferred for "concurrent" or "alongside."