Sui generis
Sui generis (; ) is a Latin phrase that means "of its (his, her, their) own kind; in a class by itself; unique."
Imperial cult of ancient Rome
"Genius" (pl. "genii") was the essential spirit and generative power – depicted as a serpent or as a perennial youth, often winged – within an individual and their clan ("gens", pl. "gentes"), such as the "Julli" (Julians) of Julius Caesar. A "paterfamilias" could confer his name, a measure of his "genius" and a role in his household rites, obligations and honours upon those he adopted. As Caesar's adopted heir, Octavian stood to inherit the "genius", heritable property and honours of his adoptive father in addition to those obtained through his own birth gens and efforts. The exceptionally potent "genius" of living emperors expressed the will of the gods through Imperial actions. In 30 BC, libation-offerings to the "genius" of Octavian (later Augustus) became a duty at public and private banquets, and from 12 BC, state oaths were sworn by the "genius" of the living emperor.