Jem

Jem is an English pet form of James, itself derived from the Late Latin Iacomus, an altered form of Iacobus, which traces back to the Hebrew name Yaakov, meaning "supplanter" or "holder of the heel." The form Jem arose naturally in English through a historical tendency to pronounce the letter a in certain positions closer to a short e sound, a feature common in many older English dialects. The name was in regular use during the medieval and early modern periods and is encountered in historical records as a familiar form used alongside the full name James. Jeremy and James are closely related names within the same broader tradition.