Mass Nouns, Abstract Nouns, and Pluralia Tantum | Icelandic Grammar

Most Icelandic nouns count cleanly: one bók, two bækur, three bækur. But a sizeable group refuses to behave. Mass nouns like vatn ("water"), mjólk ("milk"), and kaffi ("coffee") can't be counted at all — you measure them. Abstract nouns like gleði ("joy") and hamingja ("happiness") sit stubbornly in the singular. And a third class, the pluralia tantum — buxur ("trousers"), dyr ("door"), jól ("Christmas"), laun ("wages") — exist only in the plural, take plural agreement throughout, and refuse the ordinary numerals einn, tveir, þrír entirely. This page is a field guide to all three: how to quantify them, how to make them agree, and the one genuinely surprising fact — that counting a pluralia-tantum noun pulls in a whole second series of numerals.

Mass nouns: measure them, don't count them

A mass noun names a substance you think of as an undivided whole, not as a collection of units — water, milk, coffee, bread, gold, snow. Like English, Icelandic treats these as uncountable: they have no natural plural and you cannot put a cardinal numeral in front of them. You don't say "two waters"; you say "two glasses of water." The substance is quantified by a measure word plus the partitive preposition af ("of"), or by a measure word that simply takes the substance in the genitive.

The everyday pattern is [measure word] + af + [mass noun in dative]:

Má ég fá glas af mjólk?

Can I have a glass of milk? — the measure word 'glas' carries the count; the substance 'mjólk' follows 'af' in the dative. You can't say '*tvær mjólkir'.

Hún hellti upp á tvo bolla af kaffi.

She made two cups of coffee. — again the count sits on 'bolla' (cups); 'kaffi' stays singular after 'af'.

Það er ekki dropi af vatni eftir í brúsanum.

There isn't a drop of water left in the bottle. — 'dropi af vatni', a drop of water; 'vatn' is mass, quantified by the measure noun.

English speakers rarely get the concept wrong here, because English does exactly the same thing ("a glass of milk"). The trap is the preposition and case: it's af + dative (af mjólk, af vatni), not the genitive you might expect from English "of." And note that in a café you can order "einn kaffi" colloquially — Icelanders do treat a serving of coffee as countable in casual speech (informal) — but the substance itself remains uncountable.

💡

Mass nouns take af + dative: glas af mjólk, kíló af sykri, lítri af bensíni. The number lives on the measure word (glas, kíló, lítri), never on the substance. Ordering "einn kaffi" for a single coffee is fine in a café (informal), but you still can't pluralise the substance itself.

Abstract nouns: singular by default

Abstract nouns name qualities, states, and feelings rather than things you can touch: gleði ("joy"), hamingja ("happiness"), reiði ("anger"), þekking ("knowledge"), ást ("love"). Like their English counterparts, most of them are uncountable and stay singular — you have mikil gleði ("great joy"), not *tvær gleðar. They behave grammatically like mass nouns: you quantify them with adjectives of amount (mikil, lítil) rather than numerals.

Það ríkti mikil gleði á heimilinu þetta kvöld.

Great joy reigned in the household that evening. — abstract 'gleði' takes the amount-adjective 'mikil', not a numeral.

Hann talar um þetta af mikilli þekkingu.

He speaks about this with great knowledge. — abstract 'þekking', dative after 'af', stays singular.

The one thing to watch is that a few abstracts can be pluralised when they shift meaning toward "instances" — vonir ("hopes"), áhyggjur ("worries") — but these are lexical exceptions you learn one at a time, not a productive rule. The safe default is: an abstract noun is singular unless you've specifically met a plural form.

Pluralia tantum: the plural-only nouns

Now the genuinely Icelandic part. A pluralia tantum (Latin "plurals only") is a noun that has no singular at all — it exists only in the plural, even when it refers to a single object. English has a handful (trousers, scissors, glasses, pants), and crucially, when English wants to count them it reaches for the crutch "a pair of." Icelandic has its own set, and it solves the counting problem in a far more systematic way (below).

The core members to know:

Noun	Gender	Meaning	Note
buxur	feminine pl.	trousers	one garment, grammatically plural
dyr	feminine pl.	door(way)	the opening; cf. hurð 'the door leaf' (countable sg.)
jól	neuter pl.	Christmas	the holiday is always plural
laun	neuter pl.	wages, pay	your salary is grammatically plural
gleraugu	neuter pl.	glasses (spectacles)	lit. 'glass-eyes'
skæri	neuter pl.	scissors	one tool, plural form

The first rule of pluralia tantum is agreement: because the noun is plural, everything around it goes plural — the verb, adjectives, the article. There is no singular form to fall back on.

Buxurnar eru nýjar og fara þér vel.

The trousers are new and suit you well. — 'buxurnar' (buxur + plural article -nar), plural verb 'eru', plural adjective 'nýjar'. It's one garment, but everything agrees in the plural.

Dyrnar voru opnar, svo ég gekk bara inn.

The door was open, so I just walked in. — 'dyrnar' is grammatically plural ('the door[way]'), so the verb is plural 'voru' and the adjective is plural 'opnar', even though it's a single doorway.

Launin mín duga varla út mánuðinn.

My wages barely last to the end of the month. — neuter plural 'launin' with plural possessive 'mín'; 'my salary' is a plural in Icelandic.

💡

A pluralia-tantum noun has no singular, so it drags everything into the plural: verb, adjective, article, possessive. Buxurnar eru nýjar — never *buxan er ný. Treat buxur, dyr, jól, laun as permanently plural words and you'll get the agreement right automatically.

jól: a neuter plural holiday

Jól ("Christmas") deserves its own line because you'll meet it every December. It's a neuter plural, so the famous greeting agrees in the neuter plural: gleðileg jól ("merry Christmas" — literally "joyful Christmases"). The adjective gleðilegur takes its neuter plural form gleðileg to match.

Gleðileg jól og farsælt komandi ár!

Merry Christmas and a happy new year! — 'gleðileg' is the neuter plural of 'gleðilegur', agreeing with neuter-plural 'jól'. The standard seasonal greeting.

Við höldum jólin alltaf heima hjá ömmu.

We always spend Christmas at Grandma's. — 'jólin' (jól + neuter plural article -in), the accusative object; the holiday is plural throughout.

Counting pluralia tantum: the distributive numerals

Here is the fact that catches everyone. You've learned that pluralia tantum are plural — so to say "one pair of trousers" you might reach for the plural-agreeing form of "one." But the ordinary cardinal won't do the job, because einn/tveir/þrír count individual units, and these nouns have no units to count. Saying *ein buxa is doubly wrong: buxa isn't a word (there's no singular), and ein is the singular numeral.

Icelandic's solution is a dedicated second series of low numerals — the distributive (or "set") numerals — that count pairs and sets rather than units: einar, tvennar, þrennar ("one / two / three sets-or-pairs of"). These are the numerals you use with pluralia tantum, and they agree in gender and case with the noun:

Sense	with masc. (skór)	with fem. (buxur)	with neut. (gleraugu)
'one pair/set of'	einir skór	einar buxur	ein gleraugu
'two pairs/sets of'	tvennir skór	tvennar buxur	tvenn gleraugu
'three pairs/sets of'	þrennir skór	þrennar buxur	þrenn gleraugu

Ég þarf að kaupa einar buxur fyrir veturinn.

I need to buy a pair of trousers for the winter. — 'einar buxur' = one pair of trousers; the feminine distributive 'einar' agrees with feminine 'buxur'. Not '*ein buxa'.

Hún á þrennar buxur sem passa henni vel.

She has three pairs of trousers that fit her well. — 'þrennar buxur', three pairs; the distributive counts garments, the cardinal '*þrjár' would be ungrammatical here.

Tvennar dyr opnast inn í garðinn.

Two doors open into the garden. — 'tvennar dyr', two doorways; feminine distributive 'tvennar' agrees with feminine-plural 'dyr'.

This is the headline insight of the page: pluralia tantum force the distributive numeral series, a whole sub-paradigm that most courses never mention. Einar buxur, tvennir skór, þrennar dyr — once you see that the counting word itself changes shape for these nouns, the whole class stops being mysterious. The full distributive paradigm (including the genitive X-s konar phrases and the neuter "things" forms tvennt/þrennt) has its own page; here the point is just to reach for einar/tvennar/þrennar, never ein/tvær/þrjár, the moment a pluralia-tantum noun appears.

How English compares

English handles all three classes but with less grammar baked in. For mass nouns, English and Icelandic agree almost perfectly ("a glass of milk" = glas af mjólk), so the only adjustment is the af + dative pattern. For abstract nouns, both languages default to the singular, so there's little to relearn. The real gap is the pluralia tantum: English patches the counting problem with the noun "pair" ("a pair of trousers, two pairs of scissors"), an invariable crutch that agrees with nothing. Icelandic instead inflects the numeral itself (einar, tvennar, þrennar), making it agree in gender and case like any other word. So the mental shift isn't "Icelandic has weird plural-only nouns" — English has those too — it's "Icelandic counts them with a special, declining numeral rather than the word 'pair.'"

Common Mistakes

❌ Ég keypti ein buxa í gær.

Wrong twice over — 'buxa' isn't a word (no singular exists), and 'ein' is the singular numeral. Pluralia tantum take the plural distributive.

✅ Ég keypti einar buxur í gær.

I bought a pair of trousers yesterday. — 'einar buxur', the distributive 'einar' agreeing with plural 'buxur'.

The single most common error: treating buxur as if it had a singular. It doesn't — and "one pair" is einar buxur, not *ein buxa.

❌ Hún á tvær buxur.

Wrong numeral — the cardinal 'tvær' counts two single items, but 'buxur' has no countable singular. Use the distributive for pairs.

✅ Hún á tvennar buxur.

She has two pairs of trousers. — distributive 'tvennar'.

❌ Ég fékk tvær mjólkir með morgunmatnum.

Wrong — 'mjólk' is a mass noun and can't be pluralised or counted directly. Measure it.

✅ Ég fékk tvö glös af mjólk með morgunmatnum.

I had two glasses of milk with breakfast. — count the measure word 'glös', not the substance.

❌ Buxan er ný.

Agreement error — there's no singular 'buxan'; the noun is plural, so verb and adjective must be plural too.

✅ Buxurnar eru nýjar.

The trousers are new. — plural article 'buxurnar', plural verb 'eru', plural adjective 'nýjar'.

❌ Gleðilegt jól!

Agreement error — 'jól' is neuter PLURAL, so the adjective must be the neuter plural 'gleðileg', not the neuter singular 'gleðilegt'.

✅ Gleðileg jól!

Merry Christmas! — 'gleðileg', neuter plural, agreeing with plural 'jól'.

Key Takeaways

Mass nouns (vatn, mjólk, kaffi) are uncountable: quantify them with a measure word + af
- dative (glas af mjólk), never a bare numeral.
Abstract nouns (gleði, þekking, hamingja) default to the singular and take amount-adjectives (mikil gleði), not numerals.
Pluralia tantum (buxur, dyr, jól, laun, gleraugu, skæri) exist only in the plural and force plural agreement on the verb, adjective, article, and possessive — there's no singular to fall back on.
jól is neuter plural: gleðileg jól (not *gleðilegt jól).
To count a pluralia-tantum noun, use the distributive numerals einar / tvennar / þrennar ("one/two/three pairs of"), which agree in gender and case — never the ordinary cardinals ein/tvær/þrjár.
English patches the same gap with the invariable word "pair"; Icelandic inflects a dedicated numeral instead.

Now practice Icelandic

Reading grammar gets you part of the way. The exercises are where it sticks — free, no signup needed.

Start learning Icelandic→