erter is the feminine plural indefinite of ert.

ertN

Kven

hernetN

Norwegian Bokmål – Kvendict-nob-fkv/src/N_nobfkv.xml:24956Edit on GitHub Suggest

eartaN; heartaN

Norsk-nordsamisk ordbokdict-nob-sme/src/N_nobsme.xml:64793Edit on GitHub Suggest

Case	Sg	Pl
Indef	ert	erter
Def	erten / erta	ertene