Weak adjectives in oblique cases

In the previous lesson, you learned that words like þessi (this) and mín (my) trigger the weak declension for adjectives. Another extremely common trigger is the definite article.

When an adjective comes directly before a noun that has the definite article attached (like dómarinn for "the judge", or fórnarlambið for "the victim"), the adjective must use the weak declension.

Weak Oblique Endings

You already know the weak nominative endings (-i, -a, -a). In the oblique cases (accusative, dative, and genitive) singular, the weak endings are incredibly simple:

• Masculine and Neuter adjectives end in -a.
• Feminine adjectives end in -u.

Masculine and Neuter: The -a Ending

For masculine and neuter nouns, the weak adjective ends in -a no matter which oblique case is required by the verb or preposition in the sentence.

In the first example, the verb verja (to defend) triggers the accusative for a neuter noun. In the second, hjálpa (to help) triggers the dative for a masculine noun. Both adjectives simply end in -a.

Feminine: The -u Ending

For feminine nouns, the weak adjective changes to -u in all three oblique cases. Notice how the adjective ending remains exactly the same whether the noun is in the accusative (the direct object) or the genitive (triggered by the preposition án).

Handling Multiple Cases

Even in complex sentences where different prepositions force different cases, weak adjectives remain completely stable.

In the example below, the preposition í triggers the accusative (stóra réttarsalinn) and vegna triggers the genitive (gamla dómsins). Because both nouns are masculine, both adjectives simply take -a.