verb · to lock down or finalize a decision, plan, or agreement

这个方案已经封口，不再接受任何改动。

verb · of a wound, to close up and heal over

几天后，他的伤口终于封口了。

noun · to seal an envelope, bag, or container; also refers to the sealed opening itself

他在信封的封口处贴了透明胶带。

verb · to keep one's lips sealed or to prevent someone from speaking out

由于受到了威胁，他只能选择封口。