The Greek adjective dermatinos means 'made of skin' or 'leathern,' derived from derma (skin/hide). It appears in the New Testament describing John the Baptist's leather belt and in parallel with Elijah's similar garment.
John the Baptist's leather belt (zōnē dermatinē) is no incidental detail — it is a deliberate echo of the prophet Elijah (2 Kings 1:8: 'He wore a garment of hair, with a belt of leather about his waist'). The Gospel writers recognized John as the Elijah-figure prophesied in Malachi 4:5, and his clothing confirmed it. By dressing like Elijah, John embodied the prophetic office of the forerunner who prepares the way for the Lord. Simple leather clothing also signaled prophetic austerity — John was no palace-dweller but a voice from the wilderness.