Names and the Patronymic System

Icelandic names are not just cultural trivia — they are a living application of the genitive case, and getting them right is genuinely useful and genuinely tricky for English speakers. The headline facts: Icelanders mostly have no inherited family surname; instead they carry a patronymic built from their father's first name in the genitive plus -son ("son") or -dóttir ("daughter"). They are addressed, listed, and alphabetised by their first name, and — like all Icelandic nouns — names change form for case. This page shows you how the patronymic is built, why siblings can have "different surnames," and how to use names correctly in a sentence. Proper-noun declension in general is on Proper Nouns; the genitive itself on Genitive Forms.

Most Icelanders have no surname

In most of Europe, you inherit a fixed family name from your father, and it passes unchanged down the generations: a Smith's children are Smiths, and so is their grandfather. Iceland works differently. There is usually no inherited family name at all. Instead, each person's second name is a patronymic — it says whose child you are, and it is freshly formed in each generation from the father's first name.

So if a man named Jón has a son, the son's second name is Jónsson ("Jón's son"). If Jón has a daughter, hers is Jónsdóttir ("Jón's daughter"). The patronymic is not a surname you'd pass on: Jónsson's own children won't be Jónsson — they'll be named after him.

How the patronymic is built: father's name in the GENITIVE + -son / -dóttir

Here is the grammatical core, and the point most courses miss. The patronymic is father's first name in the genitive + -son or -dóttir. The -son / -dóttir part is fixed; the part that changes is the father's name, which must go into the genitive case. That genitive is the word "Jón's" — Jónsson literally means "Jón's son."

So to build a patronymic you really need to know how to form the genitive of the father's name. The genitive ending depends on the name's noun class — exactly the same classes you learn for ordinary nouns:

A few patterns to read off the table:

• Jón → Jóns: a strong masculine name that takes -s in the genitive. Add -son/-dóttir directly: Jónsson, Jónsdóttir.
• Ari → Ara: a weak masculine name (ends in -i), whose genitive ends in -a. So the patronymic is Arason, Aradóttir — Ara- not Aris-. This is the one English speakers most often get wrong.
• Guðmundur → Guðmundar: the genitive is Guðmundar, but the conventional patronymics are Guðmundsson (with -s-) and Guðmundsdóttir — names sometimes use the short -s- linking form rather than the full genitive. (*Marked forms vary by name; treat the established spelling of each name as fixed.)

The safe rule for a learner: the patronymic embeds the father's name in its genitive, and the ending you reach for is the genitive ending of that name's class. When in doubt, the everyday default for -son/-dóttir is the -s linking form for most masculine names and the full genitive for weak ones (Ara-, Sturlu-).

Matronymics: from the mother's name

The patronymic is the norm, but matronymics — formed the same way from the mother's first name — are fully accepted and increasingly common. The mechanism is identical: mother's name in the genitive + -son/-dóttir. From Anna you get the genitive Önnu (note the u-umlaut a → ö), giving Önnuson and Önnudóttir; from Sigríður → Sigríðar you get Sigríðardóttir.

Consequences: siblings differ, spouses don't share, no "Mr. Jónsson"

Three consequences follow directly, and each trips up English speakers:

1. Brothers and sisters have different "surnames." A son of Jón is Jónsson; his sister is Jónsdóttir. They share no second name, because -son and -dóttir differ by sex.

2. Spouses do not share a name. Marriage changes nothing — a woman keeps her own patronymic for life. A family of four may have four different second names.

3. There is no "Mr./Mrs. Surname." Because the second name isn't a family name, you can't address someone as "Mr. Jónsson." You use the first name — Jón, Anna — in essentially all situations, formal and informal alike. This first-name convention extends to the phone book, alphabetised lists, bylines, and even the President.

Listed and alphabetised by FIRST name

Because the second name isn't a family name, Icelandic directories alphabetise by first name. The phone book (símaskrá), library catalogues, and class lists are ordered by the given name: you look up Anna under A, Jón under J — not under their patronymic. This is the single most disorienting fact for English speakers, who instinctively file people by "surname."

Given names decline for case

Like every Icelandic noun, personal names change form for case. Jón is the nominative (subject form), but in other roles the name takes endings. For the common name Jón:

So you say að hitta Jón ("to meet Jón," accusative), að tala við Jón ("to talk to Jón"), but bíll Jóns ("Jón's car," genitive — the same Jóns that builds Jónsson) and hjá Jóni ("at Jón's place," dative). Female names decline too: Anna → Önnu (acc./dat./gen.), so Ég sá Önnu "I saw Anna."

The naming committee: Mannanafnanefnd

Iceland regulates given names through the Icelandic Naming Committee (Mannanafnanefnd), which maintains an official list of approved given names (mannanafnaskrá). A name must be able to take Icelandic grammatical endings (it has to decline), fit Icelandic spelling, and not be likely to embarrass the bearer. Parents wanting a name not yet on the list must apply to the committee for approval. The deep reason connects straight back to the grammar: because names inflect for case, a name that can't be declined would break the language's syntax — so the rule that names must be grammatically well-behaved is, at bottom, a grammatical rule, not mere bureaucracy.

Common Mistakes

Key Takeaways

• Icelanders usually have no inherited surname; the second name is a patronymic (or matronymic).
• The patronymic = parent's first name in the GENITIVE + -son / -dóttir: Jón → Jóns + son = Jónsson; Ari → Ara + son = Arason; Sigríður → Sigríðar + dóttir = Sigríðardóttir.
• Therefore siblings differ by sex (-son vs -dóttir), spouses don't share a name, and there's no "Mr. Surname."
• People are addressed and alphabetised by their first name.
• Given names decline for case: Jón / Jón / Jóni / Jóns; Anna → Önnu.
• The Mannanafnanefnd approves names — and a name must be able to decline, tying the whole system back to the genitive case.