Nennius

An ancient name with historical significance, Nennius appears in the work of the 12th-century chronicler, Geoffrey of Monmouth, in which it is borne by a prince who fought Julius Caesar's army when they invaded Britain. In addition to this, it is the name of a 9th-century Welsh monk, credited for writing the History of the Britons (also known as Historia Brittonum), though this is disputed.

The exact meaning of the name is unknown, but some sources suggest it is a Latinized form of a Brythonic name, such as Nynniaw, Ninniau, or Ninian, though this doesn't lead you to a confirmed meaning. Some possibilities are that it derives from the Old Welsh nyn/dyn and nias/dias meaning "man of the battle, man of the tumult"; from enynnu meaning "to catch fire, kindle"; or from dyddiau meaning "daylight, daytime" or "fig", though this is purely speculation.

Pronounced NEN-yus.