Used in games or contests when the result is a tie; common in rock-paper-scissors.
じゃんけんであいこだった。
It was a draw in rock-paper-scissors.
The match ended in a tie.
Used when two parties are even after settling a debt, score, or exchange; often in the phrase あいこにする.
これで貸し借りはあいこだ。
Now we're even on debts.
おごってもらったから、今度は私がおごってあいこにしよう。
You treated me, so next time I'll treat you and we'll call it even.
We tied three times at rock-paper-scissors.
Let's just call this match a tie.
We said "aiko de sho!" and played rock-paper-scissors again.
互角 describes two sides being closely matched in ability during a contest, while あいこ describes the actual result being a tie.
quits; even; square
Usually written in kana; the kanji forms 相子 and 相こ are ateji and rare.
Ateji spelling; rarely used in modern writing.
Mixed kanji-kana spelling; rarely used.
The origin is uncertain. 相子 is a conventional spelling in which 相 represents mutuality; 子 does not carry its ordinary meaning “child.”