From medieval Latin adeptus, the term now indicates the followers of a religion or secret society, but also of associations and parties. Originally, the word was used in the Middle Ages to define the alchemists who researched the philosophers' stone....

A typically semicircular architectural structure in the shape of a half cylinder, defined with a vault, also known as an apsidal basin. The apse, a typical element of Roman architecture, is most commonly found at the end of a church nave, in ancient times often facing east....