Where does “tree-hearmagh” come from?

tree-hearmagh (Manx) comes from Manx tree-, from Manx three, from Manx tree, from Old Irish trí, from Proto-Celtic trīs, from Proto-Indo-European *tréyes.

tree-hearmagh (Manx): trinomial

Definitions

trinomial

Ancestry of “tree-hearmagh”, step by step

Step	Language	Word	Meaning
1	Manx	tree-	tri-
2	Manx	three	Alternative spelling of tree
3	Manx	tree	three
4	Old Irish	trí	three
5	Proto-Celtic	trīs	three
6	Proto-Indo-European	*tréyes	—

Every word from Proto-Indo-European *tréyes →Every word from Proto-Celtic trīs →Every word from Old Irish trí →