Three of the most frequent words in Danish — som, der, and at — each do more than one job, and the jobs overlap in ways that quietly confuse learners. Som is both a relative pronoun and a comparative "as/like." Der is both a relative subject pronoun and an empty "filler" subject. At is both the complementiser "that" and the marker in front of an infinitive. Because each word looks identical across its uses, learners mix them up — and mixing them up produces ungrammatical or unintended sentences. This page collects all of them in one place and sorts them by function, so the overlaps stop being traps.
The sorting table
| Word | Function | Rough English | Example |
|---|---|---|---|
| som | relative pronoun (subject/object) | who, which, that | bogen, som jeg læste |
| som | comparative particle | as, like | hvid som sne |
| der | relative pronoun (subject only) | who, which, that | manden, der bor her |
| der | expletive / existential subject | there | der er en kat |
| at | complementiser (subordinator) | that | jeg ved, at du kommer |
| at [ɑ] | infinitive marker | to | jeg prøver at sove |
The rest of the page works through each pair.
som: relative pronoun vs comparative
Relative som
As a relative pronoun, som introduces a clause that modifies a noun, in either subject or object role. (This is its shared territory with der, covered at pronouns/relative-der-som.)
Filmen, som vi så i går, var skuffende.
The film that we saw yesterday was disappointing.
Det er hende, som altid hjælper os.
It's her who always helps us.
Comparative som
Completely separately, som is the particle of comparison — "as" or "like" — used in similes and in lige så … som equality constructions.
Hendes hænder var kolde som is.
Her hands were cold as ice.
Han løber lige så hurtigt som sin bror.
He runs just as fast as his brother.
The two som's are unrelated in meaning, but learners sometimes try to fuse them — for instance, dropping a needed lige så before the comparative som, or reading a comparative som as if it introduced a relative clause. Keep them mentally separate: relative som follows a noun and starts a clause with its own verb; comparative som follows an adjective/adverb and introduces the standard of comparison.
der: relative pronoun vs expletive
Relative der
Der is a relative pronoun too, but with one strict limit: it can only be the subject of its clause. Where som could be subject or object, der is subject-only.
Politikeren, der lovede forandring, blev ikke genvalgt.
The politician who promised change wasn't re-elected.
Expletive / existential der
The same word der also serves as a "dummy" subject — the equivalent of English "there" in "there is / there are." Here it refers to nothing; it just fills the subject slot so the real subject can come later. (See syntax/der-expletive.)
Der er noget galt med bilen.
There is something wrong with the car.
Der bor mange studerende i den her gade.
There live many students on this street. (Many students live on this street.)
These two der's are easy to tell apart in practice: the relative der always sits right after a noun and a comma, introducing a description of that noun; the expletive der typically opens a clause and is followed by a verb of existence or appearance with the logical subject after it.
at: complementiser vs infinitive marker
This is the pair that causes the most trouble, partly because the two at's are even pronounced differently.
The complementiser at — "that"
The subordinating at introduces a finite that-clause (a clause with a tensed verb). It is pronounced with a clear vowel, roughly [æd]. It is the Danish equivalent of the conjunction "that" in "I know that you're right" — and, as in English, it can often be dropped in casual speech.
Jeg håber, at du har det godt.
I hope that you're well.
Hun sagde, at toget var forsinket.
She said that the train was delayed.
The infinitive marker at — "to"
The infinitive at sits in front of a bare infinitive (a tenseless verb) and corresponds to English "to." Critically, it is pronounced differently — reduced to roughly [ɑ], almost like the conjunction og ("and"), which is also pronounced [ɑ]. This is why Danes themselves frequently confuse at and og in writing: they sound identical in speech.
Det er svært at lære dansk.
It's hard to learn Danish.
Jeg har glemt at købe mælk.
I forgot to buy milk.
The at / og spelling trap
Because infinitive at [ɑ] and og [ɑ] are homophones, the single most common native Danish spelling error is writing one for the other. The rule that resolves it: an infinitive (tenseless verb) takes at; a genuine "and" linking two equal elements takes og. (More on this contrast at choosing/at-vs-og.)
Jeg vil prøve at løbe hver dag.
I want to try to run every day. (infinitive → at)
❌ Jeg vil prøve og løbe hver dag.
Incorrect — this needs the infinitive marker at, not og.
A quick test Danes are taught: mentally insert for at or replace with another infinitive — if it still makes sense, it is at. If you can swap in a plus / and then reading with a second finite clause, it is og.
Common Mistakes
❌ Han er stærk, som en bjørn er han.
Garbled — comparative som doesn't introduce a clause like this.
✅ Han er stærk som en bjørn.
He is strong as a bear.
❌ Manden, der jeg så, var høj.
Incorrect — der is subject-only; for an object relative use som.
✅ Manden, som jeg så, var høj.
The man whom I saw was tall.
❌ Det er vigtigt og spise morgenmad.
Incorrect — infinitive marker should be at, not og.
✅ Det er vigtigt at spise morgenmad.
It's important to eat breakfast.
❌ Jeg synes at og det er en god idé.
Incorrect — only one complementiser at is needed; og is intrusive.
✅ Jeg synes, at det er en god idé.
I think that it's a good idea.
❌ Er mange mennesker til festen.
Incorrect — an existential clause needs the expletive der as subject.
✅ Der er mange mennesker til festen.
There are many people at the party.
Key Takeaways
- som = relative pronoun (after a noun) or comparative "as/like" (after an adjective/adverb) — two unrelated jobs.
- der = relative pronoun (subject-only, after a noun) or expletive "there" (existential, opening a clause).
- at = complementiser "that" (before a finite verb, pronounced [æd]) or infinitive marker "to" (before a bare infinitive, pronounced [ɑ]).
- The infinitive at [ɑ] sounds like og [ɑ], which is why even natives misspell them — decide by whether the following verb is an infinitive (→ at) or whether you are joining two equal elements (→ og).
Now practice Danish
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Start learning Danish→Related Topics
- Conjunctions: An OverviewA1 — Danish conjunctions split into coordinating (join equals, no word-order change) and subordinating (introduce subordinate clauses with subordinate word order) — and the split is worth learning for its grammar, not its meaning.
- Relative Pronouns: Der and SomB1 — Danish links relative clauses with der (subject only) and som (subject or object, and droppable when it is the object) — plus hvad, hvilket, and prepositional relatives.
- Uses of the InfinitiveB1 — Where the bare infinitive and the at-infinitive appear in Danish — after modals, after other verbs and prepositions, as subject or object, in for at / uden at / ved at, and as instructions on signs.
- Existential and Expletive DerB1 — Der as the formal subject in existential and presentational sentences — Der er en kat i haven, Der kommer en bus, Der blev sunget — and why the logical subject after it must be indefinite.
- At vs Og: The Homophone TrapA2 — How to decide between writing at and og — the most common Danish spelling error — using a simple English-substitution test.