The elder of Judah and Tamar's twins, named for the midwife's startled pun — 'how you have BROKEN OUT, a breach (perets) upon you!' — after his brother Zerah's hand appeared first, was marked with a scarlet thread, and withdrew (38:27-30). One more firstborn in this book who isn't. The name outlives the joke: Ruth ends by tracing 'the generations of Perez' ten names down to DAVID (Ruth 4:18-22), and Matthew opens the New Testament with the same line (Matthew 1:3). So the royal and messianic descent runs not through the son Judah protected nor the marriage he arranged, but through the widow he wronged. KJV spells him Pharez; Douay, through the Greek, Phares.