The Relative Clause Marker sem (and er)

Here is one of the kindest corners of Icelandic grammar. To join a relative clause — the man *that I saw, the woman **who lives here, the house **that we bought — Icelandic uses a single, unchanging word: *sem. It does not inflect for gender, it does not inflect for number, and, remarkably, it does not inflect for case. One word does the work of English who, whom, which and that all at once, and the work of German der/die/das/den/dem/deren — none of which Icelandic needs. After the grind of declining everything else, sem asks nothing of you.

sem: one word for everything

In every row the relativizer is the same three letters. Whether the antecedent is a man, a woman, a house or a group of children, and whether that antecedent plays the subject or the object inside the relative clause, sem never moves. This is the defining fact of the page, and it is genuinely the whole rule.

Subject and object relatives

A relative clause has a "gap" — the spot where the antecedent would have stood if the clause were a plain sentence. When the gap is the subject of the relative clause, sem is followed directly by the verb. When the gap is the object, the clause has its own subject and the antecedent is understood as the object.

Crucially, you do not mark this difference on sem. English barely marks it either (formal who vs whom), but German would force der vs den. Icelandic flattens both into sem and lets the clause's internal structure do the rest.

The case lives in the gap, not in sem

This is the conceptual heart of the page, and the one thing that takes practice. Because sem refuses to inflect, the case of the relativised noun is recovered from the gap inside the clause — from the silent role it plays — not from the relativizer. You must mentally fill the gap and ask "what case would the noun have had there?"

Consider maðurinn sem ég hjálpaði ("the man I helped"). Inside the clause, the verb hjálpa takes the dative, so the man is the dative object — but sem shows none of that, and the antecedent maðurinn sits outside in its own (here nominative) case. The dative is real but invisible; it lives in the gap.

In the second sentence, sakna governs the genitive, so the gap is genitive — yet you write only sem. A learner who looks for a "genitive relative pronoun" will look forever; the case is carried silently by the structure.

Preposition stranding: the natural Icelandic pattern

When the relativised noun is the object of a preposition, everyday Icelandic leaves the preposition stranded at the end of the relative clause, just as casual English does. The house I live in is húsið sem ég bý *í*.

This stranding is normal, neutral and idiomatic — not a casual lapse to be avoided. English speakers are sometimes taught that ending a clause with a preposition is "wrong," and they then bend over backwards to avoid it in Icelandic too. Don't. Húsið sem ég bý í is exactly how Icelanders speak and write.

There is a formal/literary alternative in which the preposition is fronted together with an inflected relative element — húsið í hverju ég bý — but it sounds elevated and is uncommon in speech. For A2 purposes, strand the preposition and use sem.

er: the formal and literary relativizer

Older texts, poetry, and elevated prose use er as a relative particle in place of sem — maðurinn er ég sá for maðurinn sem ég sá. It is the same syntax with a more archaic flavour. Modern spoken and written Icelandic overwhelmingly prefers sem; you should recognise er when reading the sagas, hymns or formal registers, but produce sem.

No agreement — the contrast with German and English

The single insight to carry away is absence: Icelandic builds relative clauses with no relative-pronoun agreement at all. German makes you choose among der, die, das, den, dem, deren, denen by gender, number and case; older English split who and whom. Icelandic does neither — it parks one invariant particle, sem, at the join and lets the clause-internal gap encode the case silently. Far from being a gap in the language, it is a feature: the hardest part of relative clauses in other languages has been engineered away.

Common Mistakes

The instinct to inflect the relative pronoun (carried over from German, Latin, or even Spanish el cual) is the first thing to drop. Sem has exactly one form.

Pulling the preposition up in front of sem produces ungrammatical Icelandic. Leave the preposition where it falls, at the end of the clause.

Do not borrow the question word hver ("who?") as a relative pronoun the way English reuses "who." Icelandic keeps the two jobs separate: hver asks, sem relates.

English freely drops "that" in object relatives ("the book I read"); standard Icelandic keeps sem. Don't carry the English omission across.

Resist the urge to "fill in" the gap with an extra pronoun to show its case. The gap is meant to be empty; sem plus the bare clause is complete.

Key Takeaways

• sem is the universal, invariant relativizer — one form for every gender, number and case, covering who/which/that.
• The case of the relativised noun lives in the gap inside the clause, recovered by refilling it (sem ég sakna → sakna
  • genitive); sem itself shows nothing.
• Prepositions strand at the end of the clause — húsið sem ég bý í — and this is the normal, idiomatic pattern, not an error.
• er is the archaic/literary relativizer; recognise it in old or formal texts, but produce sem.
• Icelandic has no relative-pronoun agreement — the German/Latin difficulty is simply absent here.