yellow flag
noun
1
- a ship's yellow or quarantine flag (denoting the letter Q), indicating a request for customs clearance when flown alone（商船上用的）黄旗, 检疫旗（代表字母Q, 单独悬挂时表示请求海关结关）。
1.1
- Motor Racing a yellow flag used to signal to drivers that there is a hazard such as oil or a crashed car ahead【赛车】（用以警告赛车手前有漏油或撞坏车辆等危险的）黄色信号旗。
2
- a yellow-flowered iris which grows by water and in marshy places, native to Europe黄菖蒲, 黄鸢尾。
2.1
- Iris pseudacorus, family Iridaceae.拉丁名Iris pseudacorus,鸢尾科。