Bilophodont refers to a type of tooth structure. 'Bi-' means two. A loph is a ridge. And -dont means tooth. Hence, a bilophodont is a tooth with two ridges. Bilophodont teeth are a sub-type of lophodont teeth.
bicuspids are one form of bilophodont, but it is also a very common for a premolar or molar to take this form. In the case of molars the 'ridge' may present in the form of two cusps, or points, with a low connecting bridge between them. Many bilophodont molars have four cusps, and are useful for chewing leaves and insects.
When classifying primates the bilophodont pattern is contrasted with the Y-5 molar pattern, in which there are five cusps.
Despite the fact that selenodont teeth are made up up two ridges, they are usually not called bilophodont. When talking about molars in specific, it is common to refer to the connection of cusps by a ridge as bilophodont, but the elongation of a single cusp into a ridge as a selenodont.