bi·lat·er·al / bīˈlatərəl/ • adj. having or relating to two sides; affecting both sides: bilateral hearing is essential for sound location. ∎  involving two parties, usually countries: the recently concluded bilateral agreements with Japan.DERIVATIVES: bi·lat·er·al·ly adv.

bilateral (by-lat-er-ăl) adj. (in anatomy) relating to or affecting both sides of the body or of a tissue or organ or both of a pair of organs.