| Sg. Indef. | nauðsyn |
| Sg. Def. | nauðsynin |
| Pl. Indef. | nauðsynjar |
| Pl. Def. | nauðsynjarnar |
| Sg. Indef. | nauðsynjar |
| Sg. Def. | nauðsynjarinnar |
| Pl. Indef. | nauðsynja |
| Pl. Def. | nauðsynjanna |
| Sg. Indef. | nauðsyn |
| Sg. Def. | nauðsyninni |
| Pl. Indef. | nauðsynjum |
| Pl. Def. | nauðsynjunum |
| Sg. Indef. | nauðsyn |
| Sg. Def. | nauðsynina |
| Pl. Indef. | nauðsynjar |
| Pl. Def. | nauðsynjarnar |