ei grønnsak · vegetable
Feminine (ei)
Indefinite singular
ei grønnsak
Definite singular
grønnsaka
Indefinite plural
grønnsaker
Definite plural
grønnsakene
Feminine nouns (ei) can always be written with en as well: ei bok, boka or en bok, boken. Both are correct Bokmål.
How to guess the gender Nouns: gender and articles