excreta material sweat material An excreta material which is composed primarily of sweat, an excreta consisting primarily of water as well as a smaller amount of sodium chloride that is excreted by the sweat glands in the skin of mammals. ENVO bodily fluid classes differ from UBERON's treatment of bodily fluids. UBERON refers to the substance itself ("S"). We assert that UBERON's classes are the primary compositional component of the terms in ENVO ("S material"). Use of the ENVO terms is typically recommended when you wish to indicate that there may be other materials intermixed with S.