The BackBone Thesaurus (BBT for short) is the research outcome of work undertaken by the Thesaurus Maintenance Working Group (WG), which was established within the framework of DARIAH-EU. The BBT is an overarching meta-thesaurus for humanities research data. It offers top-level-concepts (facets and hierarchies) that serve as the common ground for thesaurus building. It relies on a faceted classification, which is considered valid and consistent from a cross-disciplinary perspective. Among the major advantages of such a classification, is its potential expansion into new scientific domains in a sustainable and manageable fashion. It is important to underline that the BBT, explicitly does not require domain experts to abandon their terminology in the name of some universally accepted terminology. Rather, the core feature of the BBT is that it promotes alignment of cutting-edge terminology to well-formed general terms of the meta-thesaurus capturing general meanings. This enables collaboration and cross-disciplinary resource discovery, while ensuring compatibility with thesauri that cover highly specific and developing areas of knowledge. By design, not only can the BBT function as an overarching thesaurus for the humanities, to be used by a gradually growing community of thesauri maintainers, but it can also evolve into a distributed federated thesaurus, bringing together several specialist thesauri, under one common scheme.