ei bestemor · grandmother
Feminine (ei)
Indefinite singular
ei bestemor
Definite singular
bestemora
Indefinite plural
bestemødre
Definite plural
bestemødrene
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