| Sg | Pl | |
| Nom | jökull | jökular (rule) |
| Acc | jökul (rule) | jökula (rule) |
| Dat | jökuli (rule) | jökulum (rule) |
| Gen | jökuls (rule) | jökula (rule) |
| Sg | Pl | |
| Nom | jökullinn (rule) | jökularnir (rule) |
| Acc | jökulinn (rule) | jökulana (rule) |
| Dat | jökulinum (rule) | jökulunum (rule) |
| Gen | jökulsins (rule) | jökulanna (rule) |