This is the strong feminine class you will use most: genitive singular in -ar, nominative plural in -ir. Its members are blunt, consonant-final feminines — borg ("city"), mynd ("picture"), ferð ("trip"), vél ("machine"), þjóð ("nation") — and they share a wonderfully economical singular. In the singular, three of the four cases are the identical bare stem; only the genitive sticks out, in -ar. All the variation lives in the plural, which ends in -ir. This page drills borg and mynd, shows you with a single noun in three roles that the accusative and dative really are the nominative unchanged, and ends with the practical news that this class is the safe default for unfamiliar consonant-final feminines.
The model: borg
Here is borg ("city") in full. The singular is the headline act — watch how little it moves:
| Case | Singular | Plural |
|---|---|---|
| Nefnifall (nom.) | borg | borgir |
| Þolfall (acc.) | borg | borgir |
| Þágufall (dat.) | borg | borgum |
| Eignarfall (gen.) | borgar | borga |
Read the singular column: borg, borg, borg, borgar. The nominative, accusative and dative are the same word — the bare stem borg — and only the genitive adds -ar. This near-total syncretism in the singular is the single most relaxing fact in Icelandic feminine declension. The plural, by contrast, is fully marked: nominative and accusative borgir (the -ir that names the class), dative borgum, genitive borga.
Reykjavík er stærsta borg landsins.
Reykjavík is the country's biggest city. Nominative singular 'borg' — the bare stem, here as subject.
Ég þekki þessa borg vel.
I know this city well. Accusative singular 'borg' — identical to the nominative; the object of 'þekkja'.
Hann hefur búið í þessari borg í tíu ár.
He has lived in this city for ten years. Dative singular 'borg' after 'í' — again identical to the nominative; the preposition takes the dative but the noun's form doesn't budge.
Íbúar borgarinnar eru um þrjú hundruð þúsund.
The city's inhabitants number about three hundred thousand. Genitive singular 'borgar' (here borgarinnar, with the article) — the one singular case with an ending.
Those four sentences are the whole point of the class: the same word borg does subject, object and prepositional-object duty unchanged, and only when you say "the city's" does an ending appear.
The same pattern: mynd
Mynd ("picture, image, film") declines identically. Seeing a second noun in the same frame fixes the template:
| Case | Singular | Plural |
|---|---|---|
| Nefnifall (nom.) | mynd | myndir |
| Þolfall (acc.) | mynd | myndir |
| Þágufall (dat.) | mynd | myndum |
| Eignarfall (gen.) | myndar | mynda |
Same shape: mynd, mynd, mynd, myndar in the singular, myndir, myndir, myndum, mynda in the plural. Every cell lines up with borg.
Tókstu margar myndir í ferðinni?
Did you take many pictures on the trip? Accusative plural 'myndir' — the -ir plural; also note 'ferðinni', dative of 'ferð', another noun of this class.
Þessi mynd er frá því í fyrra.
This picture is from last year. Nominative singular 'mynd' — bare stem.
Gæði myndarinnar eru léleg.
The quality of the picture is poor. Genitive singular 'myndar' (here myndarinnar, with the article).
What English speakers get wrong: over-inflecting the singular
The biggest trap is expecting the singular to change. English speakers, drilled to think "subject vs object," instinctively look for a different accusative — but in this class there isn't one. The accusative equals the nominative. The dative equals the nominative. Three cells are one form. The reflex to "decline harder" produces wrong forms; the correct move is to leave the singular alone unless you are in the genitive.
Borgin er falleg, og ég elska borgina, og ég bý í borginni.
The city is beautiful, and I love the city, and I live in the city. Three roles — nominative 'borg', accusative 'borg', dative 'borg' — all the same word, here only distinguished by the article (-in, -ina, -inni).
That sentence is contrived to make the point, but it shows the mechanism: the only thing that changes across the three roles is the definite article ending (borgin, borgina, borginni), not the noun stem. Strip the article and you have borg three times.
The genitive -ar and the plural -ir are different things
The other classic error is letting the plural -ir leak into the genitive singular, or vice versa. They are unrelated endings that happen to both contain r:
- Genitive singular = -ar: borgar, myndar, ferðar. This is what you use after til ("to/towards"), vegna ("because of"), and to mean "of the X / the X's".
- Nominative/accusative plural = -ir: borgir, myndir, ferðir. This is "cities, pictures, trips".
Við gengum til borgar í dögun.
We walked towards the city at dawn. Genitive singular 'borgar' after 'til' — the -ar ending, singular.
Margar borgir á Íslandi eru í raun litlir bæir.
Many 'cities' in Iceland are really small towns. Nominative plural 'borgir' — the -ir plural, not to be confused with the genitive 'borgar'.
The dative plural -um and rounding
Like every strong feminine, this class forms its dative plural in -um: borgum, myndum, ferðum. When the stem contains an a, the -um rounds it to ö by u-umlaut. Most members of the class have no a (their vowel is o, y, e, é, jó…), so rounding is rarer here than in the masculines — but it does happen, most visibly in derived nouns: verslun ("shop") → dative plural verslunum (no rounding, the vowel is u), whereas a hypothetical a-stem would round. Watch for it whenever the stem vowel is a.
Hún hefur ferðast til margra borga í Evrópu.
She has travelled to many cities in Europe. Genitive plural 'borga' after 'margra' — note the bare -a genitive plural.
Í stórum verslunum er oft langt á milli deilda.
In big shops it's often a long way between departments. Dative plural 'verslunum' — the -um ending; 'verslun' is an -ir feminine (verslanir in the plural).
Why this class is your default guess
This -ir class is the productive strong feminine pattern — the one that absorbs abstract nouns and loanwords. Words coined or borrowed as consonant-final feminines tend to join it: many nouns in -un and -ing (themselves feminine) take -ir plurals (verslun → verslanir, bygging → byggingar is the -ar sub-type, so check), and fresh consonant-final feminines default here. So when you meet an unfamiliar feminine that ends in a consonant and you have no dictionary, the borg/mynd pattern — invariant singular, genitive -ar, plural -ir — is the percentage guess.
Það komu nýjar pantanir í morgun.
New orders came in this morning. Nominative plural 'pantanir' (from 'pöntun', order) — a derived feminine taking the -ir plural.
Ég þarf að bóka tvær ferðir fyrir helgina — nei, þrjár, ég gleymdi mömmu.
I need to book two trips before the weekend — no, three, I forgot Mum. Natural self-correction; 'ferðir' is the -ir plural of 'ferð'.
Common Mistakes
❌ Ég þekki þessa borgina.
Incorrect — over-inflecting: the accusative singular of 'borg' is just 'borg' (here with the article, borgina is fine, but the noun stem must not gain an extra ending).
✅ Ég þekki þessa borg.
I know this city. Accusative singular 'borg' — identical to the nominative.
❌ Using -ur in the plural: 'margar borgur'
Incorrect — this class pluralises in -ir, not -ur: 'borgir'. The -ur plural belongs to the umlaut feminines (bók → bækur).
✅ margar borgir
many cities — the -ir plural.
❌ Genitive singular in -ir: 'til borgir'
Incorrect — -ir is the PLURAL; the genitive singular is 'borgar'. 'til' takes the genitive singular.
✅ til borgar
towards the city — genitive singular 'borgar'.
❌ Dropping the genitive -ar: 'gæði mynd'
Incorrect — 'of the picture' needs the genitive singular 'myndar', not the bare stem 'mynd'.
✅ gæði myndarinnar
the quality of the picture — genitive 'myndar' + article.
❌ No rounding where the stem has a: writing a dative plural *sagum-style for an a-stem feminine
Incorrect — an a-stem strong feminine rounds a → ö in the -um dative plural, exactly like the masculines and weak feminines.
✅ -um always rounds a stem 'a' to 'ö' (e.g. sögum, götum)
Apply the u-umlaut wherever the stem vowel is a.
Key Takeaways
- This class: genitive singular -ar, nominative plural -ir (borg, borgar, borgir).
- The singular is nearly invariant: nominative = accusative = dative = bare stem; only the genitive adds -ar (borg, borg, borg, borgar).
- Across subject, object and prepositional roles the singular does not change — only the article does (borgin, borgina, borginni).
- Don't confuse the genitive singular -ar (borgar, after til) with the plural -ir (borgir, "cities").
- The dative plural is -um, and a stem a rounds to ö by u-umlaut.
- This is the productive default for unfamiliar consonant-final feminines — guess the borg/mynd pattern when in doubt.
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Start learning Icelandic→Related Topics
- Strong Feminine Nouns: OverviewA2 — The strong feminine declensions — marked by a genitive singular in -ar (or -ur/-r) and plurals in -ir or -ar — where the singular is almost invariant and all the action is in the plural and its umlaut.