noun
Usually used adverbially as 代わり番に, meaning 'by turns' or 'in alternation'.
子供たちは代わり番にブランコに乗った。
The children took turns on the swing.
代わり番に運転して長距離を移動した。
We drove long distances by taking turns at the wheel.
Compound of 代わり (substitute, replacement) and 番 (turn, watch). The exact historical derivation is uncertain, but the word has been used since at least the Edo period to mean taking turns.