Where does “latissimus” come from?

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

latissimus (English): Ellipsis of latissimus dorsi

Definitions

Step	Language	Word	Meaning
1	Latin	latissimus	widest; very wide or spacious
2	Latin	lātus	—
3	Latin	cauda	A tail
4	Proto-Italic	kaudā	tail
5	Proto-Indo-European	keh₂udeh₂	—

latissimus — Etymology, Origin & Word History | Etymology Explorer