member of a supposed secret society possessing ancient occult wisdom, 1620s, from Modern Latin rosa crucis (DuCange) or crux, in either case a Latinization of German Rosenkreuz, French rosecroix, in either case from the name of the society's reputed founder, Christian Rosenkreuz, said to date from 1484 but not mentioned before 1614. As an adjective from 1660s. Related: Rosicrucianism.
The book describing the Rosicrucians ("Fama Fraternitatis," published in 1614) is generally regarded as merely an elaborate satire on the charlatanry and credulity of the times. Books of Rosicrucian pretensions were formerly numerous in England as well as in Germany, and several have lately reappeared in the United States. [Century Dictionary, 1895]