a covering that is put over someone's head by police officers, etc. in order to stop the person spitting at them (= forcing liquid out of the mouth) or biting them

This spit hood prevents the transfer of diseases from spitting and biting. 这种口水罩可以防止因朝人吐口水或咬人而传染疾病。

Police have admitted handcuffing a disabled 11-year-old child and placing a mesh spit hood over her head. 警方承认给一名11岁的残疾儿童戴上手铐，并在她头上戴了一个网状口水罩。