late 14c., from Old French proselite (13c., Modern French prosélyte), from Late Latin proselytus, from Greek proselytos "convert (to Judaism), stranger, one who has come over," noun use of adjective meaning "having arrived," from second aorist stem of proserkhesthai "to come or go; surrender; associate with," from proti "toward" + root of eleusesthai "to be going to come," from PIE *elu-to-, from root *leudh- "to go." Originally in English "a Gentile converted to Judaism" (late 14c.).