Where does “collaterālis” come from?

collaterālis (Latin) comes from Latin lātus, from Latin cauda, from Proto-Italic kaudā, from Proto-Indo-European keh₂udeh₂.

Ancestry of “collaterālis”, step by step

Step	Language	Word	Meaning
1	Latin	lātus	—
2	Latin	cauda	A tail
3	Proto-Italic	kaudā	tail
4	Proto-Indo-European	keh₂udeh₂	—

collaterālis — Etymology, Origin & Word History | Etymology Explorer