详细解释:n. 平底玻璃杯, 一杯的容量, 杂技演员, 翻斤斗者
【机】 滚光机, 滚筒, 齿轮换向器
英语解释：
名词 tumbler:
a gymnast who performs rolls and somersaults and twists etc.a glass with a flat bottom but no handle or stem; originally had a round bottoma movable obstruction in a lock that must be adjusted to a given position (as by a key) before the bolt can be thrownpigeon that executes backward somersaults in flight or on the ground同义词：roller, tumbler pigeon