bodily fluid material tear material 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. A bodily fluid material which is composed primarily of a volume of tears, a bodily fluid consisting of a drop of the clear salty liquid secreted by glands (lacrimal glands) in the eyes. Tears wet the membrane covering the eye and help rid the eye of irritating substances.