The strong declension is the adjective's "default" set of endings — the one you reach for when the noun phrase is indefinite ("a beautiful house," "old men") and the one a predicate adjective always takes ("the house is beautiful"). It is the harder of the two declensions: where the weak declension softens almost everything to -i or -a, the strong declension carries the full weight of gender, number, and case in a rich set of consonant-heavy endings. This page lays out the whole strong paradigm for a clean model adjective, fallegur ("beautiful"), and then shows where the u-umlaut bites in a-stem adjectives like svangur ("hungry"). The pay-off worth flagging up front: the strong neuter -t you learn here is the same neuter -t that marks neuter agreement everywhere in the language — on past participles, on some pronouns, on numerals — so this one ending earns its keep far beyond adjectives.
When the strong declension is used
Use the strong forms in exactly two situations:
- Indefinite noun phrase — the adjective sits before a noun that has no article, demonstrative, or possessive: fallegur garður ("a beautiful garden"), falleg hús ("beautiful houses").
- Predicate position — the adjective comes after vera ("be"), verða ("become"), virðast ("seem") and describes the subject: garðurinn er fallegur ("the garden is beautiful") — strong even though garðurinn is definite, because the adjective is standing outside the noun phrase.
If the phrase is definite and the adjective sits inside it (after "the," "this," or "my"), you switch to the weak declension — that's the other page. Everything below is the strong set.
The full strong paradigm: fallegur
Here is fallegur in every gender, case, and number. The endings — not the stem falleg- — are what to absorb:
| Case | Masculine sg | Feminine sg | Neuter sg |
|---|---|---|---|
| Nefnifall (nom.) | fallegur | falleg | fallegt |
| Þolfall (acc.) | fallegan | fallega | fallegt |
| Þágufall (dat.) | fallegum | fallegri | fallegu |
| Eignarfall (gen.) | fallegs | fallegrar | fallegs |
| Case | Masculine pl | Feminine pl | Neuter pl |
|---|---|---|---|
| Nefnifall (nom.) | fallegir | fallegar | falleg |
| Þolfall (acc.) | fallega | fallegar | falleg |
| Þágufall (dat.) | fallegum | fallegum | fallegum |
| Eignarfall (gen.) | fallegra | fallegra | fallegra |
Notice how these endings echo the pronoun and article endings you've already met. The masculine accusative -an (fallegan) matches the demonstrative þann; the feminine dative -ri and genitive -rar (fallegri, fallegrar) match henni-type pronoun shapes; the dative plural -um and genitive plural -ra run across all three genders. The strong adjective is, historically, just the pronoun endings stuck onto an adjective stem — which is why mastering one helps the other.
The three nominative singulars — and the all-important neuter -t
The nominative singular trio is what you say most, so lock it in first: masculine fallegur, feminine falleg, neuter fallegt.
Þetta er fallegur staður á sumrin.
This is a beautiful place in the summer. Masculine nom.sg 'fallegur' agreeing with 'staður' (kk).
Hún á fallega rödd.
She has a beautiful voice. Accusative feminine 'fallega' — 'rödd' is feminine, and 'eiga' takes the accusative.
Þeir byggðu fallegt hús við ströndina.
They built a beautiful house by the shore. Neuter 'fallegt' — the strong neuter ending is -t.
The neuter -t is the single most important ending on this page. Every neuter noun forces it: fallegt hús, gott land, kalt vatn. And it's not confined to adjectives — the very same -t marks neuter agreement on past participles (það er lokað, "it's closed"), on pronouns (hvað er þetta?), and on numerals. Internalise the adjective -t and you've internalised neuter agreement across the whole grammar.
When the stem already ends in a consonant that clashes with -t, the -t assimilates: góður ("good") gives neuter gott (the ð + t fuse to tt), and kaldur ("cold") gives kalt. Fallegur ends in a vowel + g, so it just adds -t cleanly: fallegt.
The feminine and neuter umlaut: a-stems round a → ö
Fallegur has no a in its stem, so it shows no umlaut — which makes it a clean model but hides a trap. Adjectives whose stem vowel is a undergo u-umlaut: the a rounds to ö wherever a u (or a now-vanished historical u) follows in the ending. This hits two strong cells hard — the feminine nominative singular and the neuter nominative/accusative plural — plus the dative plural. Take svangur ("hungry"):
| Form | Masculine | Feminine | Neuter |
|---|---|---|---|
| nom. sg | svangur | svöng | svangt |
| nom./acc. pl | svangir | svangar | svöng |
| dat. pl (all genders) | svöngum | ||
The feminine singular svöng and the neuter plural svöng both round a → ö; so does the dative plural svöngum. This is the same u-umlaut rule you met in noun plurals — it's a single sound law operating everywhere in the language, not an adjective quirk.
Ég er svangur, eigum við ekki að fá okkur að borða?
I'm hungry, shall we get something to eat? Masculine predicate 'svangur' (male speaker).
Hún er svöng eftir langan göngutúr.
She's hungry after a long walk. Feminine predicate 'svöng' — the a rounds to ö (u-umlaut).
Barnið er svangt og þreytt.
The child is hungry and tired. Neuter predicate 'svangt' — 'barn' is neuter, so -t.
These three predicate sentences — svangur / svöng / svangt — are the everyday face of the strong declension: the adjective standing after vera and agreeing with whoever is hungry. Note that even though the woman in the second sentence might be "the woman" (definite), the predicate adjective stays strong, because it sits outside the noun phrase.
A few more cases in context
The strong declension lives in its case endings, so here it is doing real case work beyond the nominative:
Ég hitti fallegan mann í lestinni.
I met a handsome man on the train. Accusative masculine 'fallegan' — indefinite object, strong -an.
Við bjuggum í fallegu húsi við sjóinn.
We lived in a beautiful house by the sea. Dative neuter 'fallegu' after 'í' (location).
Hún gekk fram hjá fallegum görðum á leiðinni heim.
She walked past beautiful gardens on the way home. Dative plural 'fallegum' — same -um across all genders.
Common Mistakes
❌ Það er fallegur úti í dag.
Incorrect — impersonal 'það' is neuter, so the strong adjective must be neuter: fallegt.
✅ Það er fallegt úti í dag.
It's beautiful outside today. Neuter -t.
❌ Hún er svangt. / Hún er svangur.
Incorrect — a female subject needs the feminine 'svöng', with the a→ö umlaut.
✅ Hún er svöng.
She's hungry. Feminine strong, u-umlaut a → ö.
❌ Ég hitti fallegur mann.
Incorrect — the object is accusative, so the masculine strong becomes 'fallegan', not the nominative 'fallegur'.
✅ Ég hitti fallegan mann.
I met a handsome man. Accusative masculine -an.
❌ Það er góðt vín. / kaldt vatn.
Incorrect — the neuter -t assimilates after these stems: 'góður' → gott, 'kaldur' → kalt.
✅ Það er gott vín. / kalt vatn.
It's good wine. / cold water. The neuter ending fuses with the stem.
❌ Við bjuggum í fallegt húsi.
Incorrect — after 'í' (location) the phrase is dative; the dative neuter is 'fallegu', not the nominative/accusative 'fallegt'.
✅ Við bjuggum í fallegu húsi.
We lived in a beautiful house. Dative neuter 'fallegu'.
Key Takeaways
- Use the strong declension when the noun phrase is indefinite or the adjective is a predicate (after vera/verða/virðast) — even if the subject is definite.
- Nominative singular trio for fallegur: fallegur / falleg / fallegt. The neuter -t is the same -t that marks neuter agreement across the whole grammar.
- The strong endings echo the pronoun and article endings (masc. acc. -an, fem. dat. -ri, gen. -rar), so they reinforce paradigms you already know.
- a-stem adjectives undergo u-umlaut: svangur → svöng (fem. sg), svöng (neut. pl), svöngum (dat. pl) — a rounds to ö.
- The neuter -t assimilates after some stems: góður → gott, kaldur → kalt.
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- Icelandic Adjectives: Agreement and Two DeclensionsA2 — The big picture of the Icelandic adjective: it agrees with its noun in gender, number, and case, AND it has two complete declensions — strong (indefinite, gamall maður) and weak (definite, gamli maðurinn) — so a single adjective has dozens of forms, chosen by the definiteness of the whole noun phrase.
- The Weak (Definite) DeclensionA2 — The full weak adjective paradigm — used after the definite article, demonstratives, and possessives — laid out for gamall, with its tiny inventory of -i and -a (and -u) endings, the rule that definiteness drives the choice, and the redundant double-marking (gamli maðurinn) that English speakers systematically under-produce.
- u-Umlaut in Plurals and the Dative PluralA2 — The single most pervasive sound rule in Icelandic noun inflection: a stem 'a' rounds to 'ö' before a following 'u' — most reliably in the dative-plural ending -um (dögum, löndum) and in many bare plurals (barn → börn, land → lönd).