This adjective identifies someone from Adullam, the city that would later be famous as the site of David's cave refuge. In Genesis 38, it describes Hirah, Judah's companion who becomes entangled in the Tamar narrative. The term appears both with the article ('the Adullamite,' referring to Hirah) and without it ('an Adullamite man'). Adullam itself was a Canaanite city in the Shephelah, the lowland region between the coastal plain and the hill country of Judah. The gentilić form follows standard Hebrew patterns for creating ethnic or geographic identifiers.