someone who discovers the the fault or crime of another (see Molina)
Alonso de Molina:
icpaltitlan tlaaquini. encubridor tal. Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 33v. col. 2. Thanks to Joe Campbell for providing the transcription.