When someone is told to be silent, it's often for good reason. But there are other ways to convey the same message without using those two words. For instance, you could suggest that someone stay quiet or hush up. If you want them to stop talking altogether, you could ask them to keep mum or be still. Other potential synonyms for "be silent" include zip it, hold your tongue, or shush. Meanwhile, if you're trying to convey a more positive message to someone who's already quiet, you might tell them to enjoy the peace and quiet or just savor the silence.