(せなかあ)わせ

せなかあわせ
noun, no-adjective
back to back; inseparably linked (with danger or risk)
1. back to back; standing with backs touching
The physical position of two people standing or sitting with their backs against each other.
二人(ふたり)背中合(せなかあ)わせに(すわ)った。
The two sat back to back.
背中合(せなかあ)わせに()って身長(しんちょう)(くら)べた。
We stood back to back to compare our heights.
子供(こども)たちは背中合(せなかあ)わせになって、お(たが)いを()()(あそ)びをしていた。
The children stood back to back and played a game of pushing against each other.
2. inseparably linked; two sides of the same coin
Figuratively describes two things that are closely connected, especially when something positive is inseparably linked with something negative or risky.
成功(せいこう)失敗(しっぱい)背中合(せなかあ)わせだ。
Success and failure are two sides of the same coin.
幸福(こうふく)不幸(ふこう)背中合(せなかあ)わせだと()われる。
It is said that happiness and unhappiness are inseparably linked.
便利(べんり)さと危険(きけん)背中合(せなかあ)わせで、テクノロジーには(つね)にリスクが(ともな)う。
Convenience and danger go hand in hand — technology always carries risk.

Literally "backs together" — from 背中(せなか) (back) + ()わせ (together). The literal sense describes the physical position, while the figurative sense expresses the idea that two contrasting things are inseparably connected, like two sides of the same coin.

USAGE:
As a physical description (sense 1), it is used with に as an adverb: 背中合(せなかあ)わせに()つ. In the figurative sense (sense 2), it typically functions as a predicate: AとBは背中合(せなかあ)わせだ.

COMMON COLLOCATIONS:

  • 背中合(せなかあ)わせに()つ — to stand back to back
  • 背中合(せなかあ)わせに(すわ)る — to sit back to back
  • 背中合(せなかあ)わせの関係(かんけい) — an inseparable relationship

SIMILAR WORDS:

  • 表裏一体(ひょうりいったい) — two sides of one body; more formal, same figurative meaning
  • 紙一重(かみひとえ) — paper-thin difference; emphasizes how close two outcomes are