ser|o'·hetvpr1[Colloq] to get all dirty, get black with dirt 2 to take on an angry countenance: darken with anger
ser|o'·n III§ vt1[Colloq] to cover [ ] with asphalt 2 to darken, blacken 3[Fig] to shame, dishonor IV§ vi to take on an angry countenance: darken with anger