Weak Feminine Irregulars and the -na Genitive Plural

By the time you reach this page you already own the easy nine-tenths of the weak feminine declension: nominative singular -a, the whole oblique singular collapsed into -u (kona, konu, konu, konu), and a plural in -ur. The trouble lives in exactly one cell — the genitive plural — and it is worth a page of its own precisely because that cell is the single most irregular slot in the entire declension. Most learners drill the friendly -u singular, declare the class "done," and then freeze when a genitive plural turns up after til, vegna, or in a compound and the expected -a turns out to be -na: sagna, kirkna, vikna. On top of that there is one genuinely suppletive form, kvenna "women's," that comes from a different ancient stem and follows no rule at all. This page is about taming that one cell — the -na ending, the consonant changes it forces, the j-stems that drop their j before it, and the handful of suppletives you simply memorise. (The basic kona / gata paradigm and the a → ö u-umlaut are on the weak feminine page; here we go straight to the genitive plural.)

The default is -na, not bare -a

The first correction to make is conceptual. Across the noun system the genitive plural is overwhelmingly bare -a (hesta, borga, barna), and that lulls English speakers into expecting *konaa / *saga for the weak feminines too. For this class the default is different: the weak feminine genitive plural ending is -na, and the stem vowel usually syncopates (drops out) before it. So the genitive plural of saga "story" is not *saga but sagna; of vika "week", vikna; of klukka "clock", klukkna. The -na is the rule here, not a sprinkling of exceptions.

Read down the "what happens" column and the shape of the cell becomes clear: take the stem, drop the linking vowel, add -na. Sag- + -na → sagna. Vik- + -na → vikna. The a you see in the nominative singular is a declensional ending, not part of the root, so it disappears before -na rather than fusing into the bare -a you might expect from other classes.

The -ja stems lose their j: kirkja → kirkna

A large and high-frequency subgroup of weak feminines ends in -ja: kirkja "church", smiðja "smithy, workshop", brynja "coat of mail", gyðja "goddess". These behave like the others through the singular and most of the plural, but the genitive plural drops the j entirely. Kirkja does not give *kirkjna — the j cannot stand before the -na cluster, so it falls out and you get kirkna. The same happens to smiðja → smiðna. This is not an arbitrary exception: the j survives only before back vowels (a, u, o), and the -na ending presents a consonant, so the j has nothing to glide onto and disappears.

Notice that the j is alive and well in kirkju and kirkjur — before the back vowels u — and vanishes only in the genitive plural kirkna, where the next sound is the n of the ending. So a learner who knows kirkju and kirkjur still has to learn kirkna separately, because the j the whole rest of the paradigm displays is exactly the segment that drops here.

The suppletive one: kona → kvenna

Kona "woman" is the form every learner meets first and gets wrong most often, because its genitive plural is not built from the stem kon- at all. It is kvenna, from the ancient stem kven- (the same root that gave English queen and quean). You cannot derive it; the rest of the paradigm is kona, konu, konur, konum, and then the genitive plural lurches to a stem you have never seen elsewhere in the word. It even doubles the n before the ending: kven- + -na → kvenna. Memorise it as a fixed item, because it appears constantly — réttindi kvenna "women's rights", samtök kvenna "an association of women", fjöldi kvenna "a number of women".

A second suppletive worth flagging is the kinship term móðir "mother". It is not a plain weak feminine (its singular is irregular), but its genitive plural patterns the same way: the plural runs mæður, mæður, mæðrum, and the genitive plural is mæðra. The takeaway is the same — the genitive plural is the cell where the irregularity, when there is any, surfaces.

Why the genitive plural is the hard cell

There is a clean reason this one slot concentrates all the trouble. Everywhere else in the weak feminine paradigm the ending is a single vowel — -a, -u, -ur, -um — and a single vowel glides smoothly onto the stem with no fuss. The genitive plural is the only cell whose ending begins with a consonant (the n of -na). A consonant ending forces three things at once: the linking stem vowel drops (syncope: sag-na), any j in a -ja stem is squeezed out (kirk-na), and a stem-final consonant may assimilate or double. So all the morphological "action" of the declension is packed into the cell where a consonant ending meets the stem. Knowing that — that consonants at the boundary cause the changes — lets you predict them rather than memorise each one: a -ja stem will lose its j, an a-stem will syncopate, and only the genuinely suppletive kona / móðir have to be banked separately.

How English misleads you here

English has no case system at all, so the genitive plural is a foreign idea to begin with: "women's", "stories'", "churches'" all use the same possessive -'s (or bare -' after a plural -s) bolted onto an unchanged stem. There is nothing in English to suggest that the form of the word itself should change inside the genitive — that story should become sagna or church become kirkna. The Icelandic genitive plural is therefore doubly alien: it is a case English doesn't mark morphologically, and it triggers stem changes English never produces. The discipline is to stop treating the genitive plural as "the plural plus a possessive marker" and start treating it as its own cell with its own ending (-na) and its own consonant adjustments — learned alongside the noun, not assembled from the plural at the moment of speaking.

Common Mistakes

Key Takeaways

• The genitive plural is the single most irregular cell of the weak feminine declension; the friendly -u singular tells you nothing about it.
• The weak feminine genitive plural ending is -na (not the bare -a of other classes), and the stem vowel syncopates before it: saga → sagna, vika → vikna, klukka → klukkna.
• -ja stems drop their j before -na: kirkja → kirkna, smiðja → smiðna (the j survives only in kirkju, kirkjur).
• kona → kvenna is suppletive — a different stem (kven-), to be memorised; móðir → mæðra is the kinship parallel.
• The cell is hard because its ending begins with a consonant (-na), which forces syncope, j-loss, and assimilation all at once — learn the genitive plural with the word, don't build it from the plural on the fly.