Transferred use of the surname, originally a local name for someone who lived in a dale or valley. It is now fairly commonly used as a given name, along with other monosyllabic surnames of topographical origin (see for example Dell and Hale).
German: 1. perhaps a derivative of the Old High German personal name Cazo, of uncertain origin (see Kase 1). 2. Silesian (also Ketzer): from Middle High German ketzer ‘heretic’, ‘freethinker’. 3. Germanized form of Sorbian kacor or Czech kačer ‘drake’ (see Kaska 2).