"Lady" would later gain an -s genitive ending, and therefore the name means "Lady's day."

Historically, the similarity of the accusative and genitive endings is coincidental.

Animate nouns, that is nouns representing living things, take the genitive ending in the accusative case.

Here the relationship is shown by the genitive ending -in added to the first noun; the second noun has the third-person suffix of possession -(s)i.

The genitive ending is irregular, /mo/, for singular f-class nouns, but /-e/ in all others (identical to the ergative ending).

Surnames from either category are formed using nouns, adjectives, a number of suffixes and endings such as the absolutive ending -a, the relational suffix -ko and the genitive ending -ren.

The last of these is interesting in that the scientist who described it has used the masculine genitive ending 'i' instead of the feminine 'ae', showing an assumption that the collector must have been a man.

The form is archaic in Latin, preserving the old genitive ending in -ās (see Latin declension), whereas in classical Latin the normal genitive ending was -ae.

In such lexicalized expressions remnants of strong and weak nouns can be found too, e.g. in het jaar des Heren (Anno Domini), where "-en" is actually the genitive ending of the weak noun.

As Curme puts it, "The s-genitive was doubtless felt by many as a contraction of the his-genitive, which strengthened the tendency to place an apostrophe before the genitive endings" (as an indication of an elided "his").

Thus, lagau, the genitive of laag[a] place is in underlying form laaga+ngu; the full form of the genitive ending -ngu is only retained where the nominal has a monosyllabic stem (see the section on Nominal Morphology).