The genitive marks possession. In the first declension singular, the genitive will end in -ae.

Terra agricolae = The farmer’s land.

The object being possessed comes before the possessor. That means that the actual noun in the genitive (agricolae) will come second.

The -ae ending is also the nominative plural of the first declension. This may seem confusing, but the functions for the nominative plural and the genitive singular are so different, that it probably won’t be that difficult to distinguish between the two :

1) Sunt nautae = They are sailors (nominative)

2) Scapha nautae = The sailor’s boat (genitive)

Nautae ends in -ae in both sentences, but they function differently in each sentence. The nautae in the first sentence is in the singular nominative of the first declension and the second sentence is in the genitive singular of the first declension.

The plural gentive of the first declension ends in -ārum.

Schola puellārum = The girls’ school

Here, the gentive plural -ārum was used because there is more than one girl doing the possessing.

The gentive plural of the first declension has a unique ending so it’ll be easy to spot. Also, the endings for the object being possessed in all these sentences have not changed.

Here are some exercises for practice :

1) Familia pīrātae

2) Casa poētārum

3) Pecūnia fēminae

Here are the answers to the exercise :

1) The pirate’s family

2) The poets’ house

3) The woman’s money