ei vakt · shift (at work)
Feminine (ei)
Indefinite singular
ei vakt
Definite singular
vakta
Indefinite plural
vakter
Definite plural
vaktene
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