noun
thirteen orphans; winning hand with one of each terminal and honor tile
A special mahjong hand consisting of one of each terminal (1 and 9) and honor tile, plus an extra matching tile. Known as a limit hand (役満).
from Chinese
See also: 国士無双
十三ヤオ九は、麻雀の役満の中でも特に珍しい手役です。
Thirteen orphans is a particularly rare limit hand among mahjong yakuman.
彼は最後の一牌で十三ヤオ九を完成させた。
He completed the thirteen orphans hand with the very last tile.
Another name for the same hand, often used interchangeably. 十三ヤオ九 is the Chinese-derived term, while 国士無双 is a Japanese alternative name.
From Chinese 十三幺九 (shísān yāo jiǔ), literally 'thirteen one-nine', referring to the thirteen terminal and honor tiles required for the hand.