The Greek word derma refers to skin or animal hide. It appears in Hebrews 11:37 in the catalog of faith heroes who wandered in sheepskins and goatskins — destitute, persecuted, and mistreated for their faith. The word gives us our English prefix 'derm-' (relating to skin).
The mention of sheepskins and goatskins in Hebrews 11 is a stark image of radical poverty accepted for the sake of faith. These heroes of faith traded the comforts of the world for the discomfort of animal hides because they were 'looking forward to the city with foundations, whose architect and builder is God' (Hebrews 11:10). The skin covering also echoes Genesis 3:21, where God provided animal skins to cover the shame of Adam and Eve — the first act of sacrifice covering human inadequacy. Ultimately, it points to the covering that Christ provides through His sacrifice.