The Silencing Charm (incantation: Silencio) is a charm that renders the victim temporarily silent. It works on both Beasts and Beings. It is taught to fifth-year students at Hogwarts School of Witchcraft and Wizardry in Charms. In order for this charm to be most effective, the witch or wizard must move their wand using a sharp jab, rather than a sort of wave.
Voldemort used this on the defenders of Hogwarts twice during the Battle of Hogwarts, but thanks to Harry's sacrificial protection, it didn't hold.