This is a lookup page, not a teaching page. The why behind each ending lives on the strong declension and weak declension pages; here the two full grids sit side by side so you can find any cell fast and, just as importantly, compare them. Laid out together, one fact jumps out: the weak grid is almost empty of distinct forms (it's mostly -i / -a / -u), while the strong grid carries the real weight. That tells you where to spend your effort — the strong declension plus knowing when to switch is the whole job.
First decide: strong or weak?
Before you read off an ending, decide which grid you're in. The choice is driven by definiteness of the noun phrase, not by the adjective's meaning.
| Use the STRONG grid when… | Use the WEAK grid when… |
|---|---|
| the noun phrase is indefinite (no article/demonstrative/possessive): fallegur garður | the phrase is definite via the suffixed article: fallegi garðurinn |
| the adjective is a predicate (after vera, verða, virðast) — even if the subject is definite: garðurinn er fallegur | the phrase opens with a demonstrative (þessi, sá) or possessive (minn): þessi fallegi garður |
The STRONG grid (indefinite / predicate): fallegur
| Case | Masc. sg | Fem. sg | Neut. sg |
|---|---|---|---|
| nom. | fallegur | falleg | fallegt |
| acc. | fallegan | fallega | fallegt |
| dat. | fallegum | fallegri | fallegu |
| gen. | fallegs | fallegrar | fallegs |
| Case | Masc. pl | Fem. pl | Neut. pl |
|---|---|---|---|
| nom. | fallegir | fallegar | falleg |
| acc. | fallega | fallegar | falleg |
| dat. | fallegum | fallegum | fallegum |
| gen. | fallegra | fallegra | fallegra |
Two things to mark in this grid. The neuter is -t in both the nominative and accusative singular — fallegt — and this is the same neuter -t that marks neuter agreement everywhere in the language. And the dative plural -um and genitive plural -ra run identically across all three genders, so the bottom two rows of the plural grid collapse into one shape each.
Þetta er fallegur garður.
This is a beautiful garden. — strong masc. nom. sg, indefinite phrase.
Þeir byggðu fallegt hús við sjóinn.
They built a beautiful house by the sea. — strong neuter -t.
Ég hitti fallegan mann í lestinni.
I met a handsome man on the train. — strong masc. acc. -an, indefinite object.
Húsið er gamalt en fallegt.
The house is old but beautiful. — predicate adjectives stay strong even though 'húsið' is definite.
The WEAK grid (definite): fallegi
| Case | Masc. sg | Fem. sg | Neut. sg | Plural (all genders) |
|---|---|---|---|---|
| nom. | fallegi | fallega | fallega | fallegu |
| acc. | fallega | fallegu | fallega | |
| dat. | fallega | fallegu | fallega | |
| gen. | fallega | fallegu | fallega |
Now see why the weak declension is the easy half. The masculine nominative singular is the only -i form (fallegi); almost everything else in the singular is -a; the feminine oblique (acc./dat./gen.) is -u; and the entire plural — all three genders, all four cases — is one form, fallegu. Four strings (fallegi, fallega, fallegu) cover the whole grid.
Remember the double-marking: a weak adjective requires the noun to keep its article (or a demonstrative/possessive to be present). It's fallegi garðurinn, never fallegi garður.
Fallegi garðurinn hennar er fullur af rósum.
Her beautiful garden is full of roses. — weak masc. nom. 'fallegi' + article 'garðurinn'.
Ég sá fallegu konuna aftur í dag.
I saw the beautiful woman again today. — weak fem. acc. 'fallegu' + article 'konuna'.
Þessi fallegu hús eru öll friðuð.
These beautiful houses are all protected. — weak plural 'fallegu' after demonstrative 'þessi'.
Where the u-umlaut bites (a-stem adjectives)
The model fallegur has no a in its stem, so it shows no umlaut — convenient, but it hides a trap. Adjectives whose stem vowel is a round it to ö wherever the ending contains (or historically contained) a u. Use svangur ("hungry") and gamall ("old") to see the affected cells:
| Cell | Plain stem | a-stem with umlaut |
|---|---|---|
| strong fem. nom. sg | falleg | svöng (← svangur) |
| strong neut. nom./acc. pl | falleg | svöng |
| strong dat. pl (all genders) | fallegum | svöngum |
| weak fem. oblique sg | fallegu | gömlu (← gamall) |
| weak plural (all) | fallegu | gömlu |
The pattern: any -u ending (and the strong feminine/neuter cells that historically had one) rounds a → ö. It's the same u-umlaut sound law you meet on noun plurals — not an adjective quirk.
Hún er svöng eftir göngutúrinn.
She's hungry after the walk. — strong fem. 'svöng', a→ö umlaut.
Gömlu mennirnir spila brids á hverjum degi.
The old men play bridge every day. — weak plural 'gömlu', a→ö umlaut.
How to read off a cell (the routine)
- Strong or weak? Check the phrase: indefinite or predicate → strong grid; definite (article / þessi / minn) → weak grid.
- Gender — match the noun's gender (the same one that decided its article).
- Number — singular or plural.
- Case — whatever the verb or preposition assigns to the noun.
- a-stem? If the stem vowel is a and the ending has a u, round a → ö.
Common Mistakes
❌ Húsið er fallegur.
Incorrect — predicate with a neuter subject needs the strong neuter -t: fallegt.
✅ Húsið er fallegt.
The house is beautiful.
❌ Fallegi garður.
Incorrect — a weak adjective requires the article on the noun.
✅ Fallegi garðurinn.
The beautiful garden.
❌ Þessi fallegur bíll.
Incorrect — after the demonstrative 'þessi' the phrase is definite, so the adjective goes weak: fallegi.
✅ Þessi fallegi bíll.
This beautiful car.
❌ Hún er svangur.
Incorrect — a female subject needs the feminine strong 'svöng', with a→ö umlaut.
✅ Hún er svöng.
She's hungry.
❌ Ég hitti fallegur mann.
Incorrect — the object is accusative, so the strong masculine is fallegan, not the nominative fallegur.
✅ Ég hitti fallegan mann.
I met a handsome man.
Key Takeaways
- Choose the grid by definiteness: indefinite/predicate → strong; definite (article, demonstrative, possessive) → weak.
- The weak grid is tiny — fallegi (one cell), fallega (most), fallegu (fem. oblique + whole plural). The real learning load is the strong grid plus knowing when to switch.
- Strong neuter -t (fallegt) is the same -t marking neuter agreement across the grammar; strong dat. pl. -um and gen. pl. -ra are uniform across genders.
- a-stem adjectives round a → ö in any -u cell: svöng, svöngum, gömlu.
- Predicate adjectives are always strong, even with a definite subject: húsið er fallegt.
Now practice Icelandic
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Start learning Icelandic→Related Topics
- The Strong (Indefinite) DeclensionA2 — The full strong adjective paradigm — used when the noun phrase is indefinite and for predicate adjectives — laid out for fallegur across all genders, cases, and numbers, with the neuter -t, the consonant-heavy feminine and genitive endings, and the u-umlaut that surfaces in a-stem adjectives like svangur → svöng.
- 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.