the.com/melanin

means The natural pigment, made by cells called melanocytes, that gives skin, hair, and eyes their color and helps absorb UV radiation.

from From Greek 'melas/melanos,' meaning black or dark — the same root behind words like 'melancholy' (literally 'black bile') and 'melanoma.' The '-in' ending marks it as a chemical substance, a 19th-century naming convention for isolating and classifying biological compounds. So the word itself is just 'dark stuff,' named plainly by scientists who noticed what it did before they knew why.