The Collaborative International Dictionary of English v.0.48:

Carolus \Car"o*lus\, n.; pl. E. Caroluses, L. Caroli. [L.,
   Charles.]
   An English gold coin of the value of twenty or twenty-three
   shillings. It was first struck in the reign of Charles I.
   [1913 Webster]

         Told down the crowns and Caroluses.      --Macawlay.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Carolus
    n 1: king of the Franks and Holy Roman Emperor; conqueror of the
         Lombards and Saxons (742-814) [syn: Charlemagne,
         Carolus, Charles, Charles I, Charles the Great]