Where does “iwi” come from?

Iwi comes from Māori iwi, from Proto-Oceanic suʀi, though the original meaning is not documented.

iwi (English): A Maori tribe

Definitions

Step	Language	Word	Meaning
1	Maori	iwi	extended kinship group, tribe, nation, people,...
2	Proto-Polynesian	*hui	—
3	Proto-Oceanic	suʀi	thorn, splinter, fish bone
4	Proto-Central-Eastern Malayo-Polynesian	*zuʀi	—
5	Proto-Malayo-Polynesian	duʀi	—
6	Proto-Austronesian	duʀi	thorn

iwi — Etymology, Origin & Word History | Etymology Explorer