Where does “Cassius” come from?

Cassius is an English name derived from the Latin name Cassius, of unknown ultimate origin.

Ancestry of “Cassius”, step by step

Step	Language	Word	Meaning
1	Latin	Cassius	—
2	Latin	cassus	hollow, empty, devoid of something; lacking;...
3	Latin	cadō	—
4	Proto-Italic	kadō	fall, sink
5	Proto-Indo-European	ḱad-	to fall