someone who goes to a party or other event when they have not been invited

The party was ruined by a couple of rowdy gatecrashers. 聚会被几个吵吵闹闹的不速之客破坏了。

There were at least forty people at the party, some of them gatecrashers. 派对上至少有四十个人，其中一些是不请自来的。