expression, ichidan verb
synchronize breathing with the opponent before a sumo match
Sumo term: the two wrestlers match their breathing rhythm just before the initial charge. Rarely used outside sumo contexts.
力士たちは仕切り線で息を合わせる。
The sumo wrestlers synchronize their breathing at the starting lines.
Compound of 息 (breath) + を + 合わせる (to match). The expression originates from sumo, where wrestlers align their breathing before a bout.