noun
dora tile revealed after a kong
In Japanese mahjong, when a player declares a kong (槓), an additional dora indicator is flipped, increasing the number of dora tiles in play.
槓をすると槓ドラがめくられる。
When you declare a kong, a new dora indicator is flipped.
裏ドラ are hidden dora indicators revealed only after a win, whereas 槓ドラ are revealed during play after a kong.
Compound of 槓 (kan, 'kong') and ドラ (dora, 'bonus tile'), a mahjong term.