A lottery is a type of gambling game in which people buy numbered tickets. Several numbers are then chosen, and the people who have those numbers on their tickets win a prize.
例句
...the national lottery.国家博彩
N-SING
听天由命的事；全凭运气的事
If you describe something as a lottery, you mean that what happens depends entirely on luck or chance.
例句
The stockmarket is a lottery...股市买卖全看运气。Which judges are assigned to a case is always a bit of a lottery.一个案子安排哪些法官来审理，往往有点看运气。