Irregular kinship nouns (faðir, móðir)

Irregular Kinship Nouns Ending in -ir

The core family words faðir (father), móðir (mother), bróðir (brother), systir (sister), and dóttir (daughter) share an irregular singular declension. The nominative ends in -ir, while the accusative, dative, and genitive cases all end in -ur (often with a vowel shift in the stem).

NominativeAccusative, Dative & Genitive
faðirföður
móðirmóður
bróðirbróður
systirsystur
dóttirdóttur

The verb líkjast (to resemble) governs the dative case. Notice how faðir becomes föður:

My brother resembles our father.
Bróðir minn líkist föður okkar.

The preposition frá (from) also takes the dative:

Did you inherit this from your mother?
Erfðir þú þetta frá móður þinni?

Extended family words like langafi (great-grandfather) follow standard weak declensions. Here, dóttir remains in the nominative as the subject:

My daughter never met her great-grandfather.
Dóttir mín hitti aldrei langafa sinn.

To show possession (genitive case), these -ir nouns use that exact same -ur form:

My father's relatives are visiting us.
Ættingjar föður míns eru að heimsækja okkur.
My mother is thinking about my sister's upbringing.
Móðir mín er að hugsa um uppeldi systur minnar.

Direct objects take the accusative case, which is again identical to the dative and genitive:

The only child has no brother or sister.
Einkabarnið á engan bróður eða systur.

The Word for Son

The word sonur (son) has its own unique singular declension:

  • Nominative: sonur
  • Accusative: son
  • Dative: syni
  • Genitive: sonar

The adjective skyldur (related to) takes the dative case. Notice the dative form syni:

Is this man related to your son?
Er þessi maður skyldur syni þínum?
The son resembles his father because of the upbringing.
Sonurinn líkist föður sínum vegna uppeldisins.

Lineage

To talk about your family's history or roots, use the feminine noun ættin (the lineage):

My lineage comes from Iceland.
Ættin mín kemur frá Íslandi.