The design of business models is of decisive importance and as such it has been a major research theme in service and particularly electronic markets. Today, different definitions of the term and ideas of core constructs of business models exist. In this paper we present a unified vocabulary for business models that builds upon the elementary perception of three existing, yet very dissimilar ontologies for modeling the essence of a business. The resulting unified business model vocabulary not only condenses existing knowledge, but also tries to concatenate and (thematically) group the identified constructs into domain, enterprise, and value concepts. The resulting vocabulary helps business model designers in shaping the basic notions of their businesses.