side bet matching a player's wins/losses
In mahjong, a spectator's bet that mirrors the point gains and losses of a specific player. Not a standard gambling term outside mahjong.
He placed a side bet on his friend's game and went through ups and downs with every hand.
Standard kanji spelling for this mahjong term.
Variant spelling with katakana for ウマ, sometimes seen in mahjong contexts.
Compound of 外 (そと, 'outside') and 馬 (うま), literally 'outside horse'. The exact derivation is uncertain, but it likely refers to a bet placed from the sidelines, akin to an outsider's wager.