Fitz, n.

noun

(fits, 108), n. [Norm. Fr. fāz, fiuz, O. Fr. fils, fius, fix, flex, N. Fr. fils, son, from Lat. filius.] A son;—used in compound names, and, in England, of the illegitimate sons of kings and princes of the blood; as, Fitzroy, the son of the king, Fitzclarence, the son of the duke of Clarence.