black-mouthed
/ˈblakˌmaʊðd/adjective
Having a black mouth; (figurative ) slanderous; foul-mouthed.
Origin
Mid 16th century; earliest use found in John Heywood (c1496–c1578), playwright and epigrammatist. From black + mouthed. In black-mouthed dogfish after scientific Latin melanostomus.