Where does “claustrum” come from?

claustrum (Late Latin) comes from Latin claustrum, from Latin claudere, from Latin claudo, from Proto-Italic klaudō — close.

Ancestry of “claustrum”, step by step

Step	Language	Word	Meaning
1	Latin	claustrum	a bar, band, bolt; gate, door, bulwark; enclosure
2	Latin	claudere	present active infinitive of claudō;...
3	Latin	claudo	I shut, close, lock; I imprison, confine; I...
4	Proto-Italic	klaudō	close