Danish plurals

Danish plurals are usually formed in three ways:  with -e or -er added to the base or a form which is identical to the singular.  The number of plurals which do not add a suffix to the base is relatively small.  Thus, the majority of Danish plurals end in -e or -er.

The following nouns add -er:

alligator alligatorer (alligator/alligators)
bil biler (car/cars)
ged geder (goat/goats)
kylling kyllinger (chicken/chickens)
problem problemer (problem/problems)

The following nouns add -e:

dag dage (day/days)
fugl fugle (bird/birds)
hest heste (horse/horses)
hund hunde (dog/dogs)
stol stole (chair/chairs)

These nouns are invariable in singular and plural:

ben ben (leg/legs)
mus mus (mouse/mice)
ord ord (word/words)
sko sko (shoe/shoes)
sten sten (stone/stones)

Danish nouns which do not add a suffix to form the singular and plural are usually monosyllabic.  With nouns which add -e or -er to form the plural, it is necessary to memorize.  In Norwegian, however, -er is the most common plural suffix.  In Norwegian, the plurals of dag, fugl, hest, hund, and stol are dager, fugler, hester, hunder, and stoler.  Formation of the plural is thus more complex in Danish than in Norwegian.