77. oxi (ox) has pl. öxn.

78. herra (lord) is indeclinable in the sg.

Weak Neuters

SingularPlural
Nom.hjart-a (heart)hjǫrt-u
Acc.hjart-ahjǫrt-u
Dat.hjart-ahjǫrt-um
Gen.hjart-ahjart-na

79. So also auga (eye).

Weak Feminines

SingularPlural
Nom.tung-a (tongue)tung-ur
Acc.tung-utung-ur
Dat.tung-utung-um
Gen.tung-utung-na

80. So also stjarna (star) pl. stjǫrnur, kirkja (church), gen. plurals stjarna, kirkna.

Sg. Nom.ęlli (old age)
Acc.ęlli
Dat.ęlli
Gen.ęlli

81. So also glęði (joy) and many abstract nouns.