προσήλυτον, [1 verse](adj sg masc acc) "Proselyte" is  proselytos, which means "one that has arrived at a place," "sojourner," "a newcomer," and, from the NT use, "convert," "proselyte," and "one who has come from the Gentiles to become a Jew."  - The word translated as "proselyte," translated as "convert" in the NIV, shows up in Greek the first time here. It was apparently a new idea in Jesus's era, appearing only in the NT (here and in Acts), and in a few early Christian writers. It is a form of the common verb meaning "showing up like."