| Sg | Pl | |
| Nom | systir | systirar (rule) |
| Acc | systur (rule) | systirar (rule) |
| Dat | systir (rule) | systirum (rule) |
| Gen | systirar (rule) | systira (rule) |
| Sg | Pl | |
| Nom | systirin (rule) | systirarnar (rule) |
| Acc | systurina (rule) | systirarnar (rule) |
| Dat | systirinni (rule) | systirunum (rule) |
| Gen | systirarinnar (rule) | systiranna (rule) |