In ecclesiology, a catechumen (/ˌkætɨˈkjuːmən, -mɛn/; via Latin catechumenus from Greek κατηχούμενος katēkhoumenos, "one being instructed", from κατά kata, "down" and ἦχος ēkhos, "sound") is a person receiving instruction from a catechist in the principles of the Christian religion with a view to baptism. The title and practice is most often used by Orthodox Christians and by Roman Catholics.