"Skingills" is a curious word, often confused with either "skillings" or "skimmings". The correct spelling is /skɪnˈɡɪlz/ and refers to the skins, usually of salmon, which are used in the production of gelatin. The plural form of "skin" is "skins", indicated by the "s" at the end, while "gills" refers to the flap-like respiratory organs found in fish. Together, "skingills" literally means "salmon skins with gills". It's a niche term, but an interesting one nonetheless.