Oscausi is the incantation of a dark charm that can be used to seal someone's mouth shut. The victim's mouth will appear as if it was never there, with skin covering the area. The victim will also be muted as a consequence.
This spell was used by Leta Lestrange on a girl from Gryffindor when they were both in their third year at Hogwarts School of Witchcraft and Wizardry. The Gryffindor girl was speaking spitefully of Lestrange behind her back until Lestrange emerged from hiding nearby, and muted the Gryffindor girl with this spell. Minerva McGonagall reversed the spell, but when the girl began to complain about Leta further, the irritated McGonagall recast the spell.
Oscausi is possibly derived as a portmanteau of os, Latin for "mouth", and clausi (a conjugated form of claudo), Latin for "I shut". It may additionally be a pun or wordplay on scusi, the Italian interjection for "excuse me".
Similar spells used to silence targets:
- Fantastic Beasts: The Crimes of Grindelwald - The Original Screenplay (First appearance)
- Fantastic Beasts: The Crimes of Grindelwald
- Fantastic Beasts: The Crimes of Grindelwald: Magical Movie Handbook