Where does “lhean” come from?

lhean (Manx) comes from Old Irish lethan, from Proto-Celtic ɸlitanos, from Proto-Indo-European pl̥th₂-enos, from Proto-Indo-European pleth₂- — flat.

lhean (Manx): wide, broad; broad

Definitions

Step	Language	Word	Meaning
1	Old Irish	lethan	broad, wide
2	Proto-Celtic	ɸlitanos	broad, wide
3	Proto-Indo-European	pl̥th₂-enos	—
4	Proto-Indo-European	pleth₂-	flat

lhean — Etymology, Origin & Word History | Etymology Explorer