Eumops glaucinus is a medium-sized
mastiff bat, but its size varies across its range. It is roughly long and between in weight, with pregnant females sometimes heavier. The male is generally larger than the female. The species has a short, shiny
pelage of bicolored hairs that are lighter at the bases, and the overall coat color can be black, brown, grayish, or cinnamon. The underparts are duller and paler. The bat has a long snout. It lacks a leaf-shaped nose appendage and protruding upper lip, but it has a keel above the eye. The ears are about in length and are wider than long. They are joined to form the "
bonnet" shape. The wingspan is about . The wings are narrow, as in other mastiff bats. The wings are adapted to long but rapid flights, especially in open areas. This bat has a
musky odor. The male has a
gular-thoracic gland of unknown function; it may be used to mark females or territory. ==Systematics==