Forming plurals and genitives of nouns

In order to form plurals, Peano's Latino Sine Flexione added an -s to the end of words. The form that's created often corresponds to the plural accusative or sometimes the plural nominative unless the noun is originally neuter in Latin or Greek.

Plural examples: rosa -> rosas; amico -> amicos; nocte -> noctes; manu -> manus.

The following changes can be used to form the singular genitive corresponding closely to the original Latin: -a -> -ae; -o -> -i; -e -> -is; -u -> -ui; -e (hard as in the short words re or die) -> -ei.

To make the plural genitive, the following changes can be made: -o, -a, or hard -e -> add -rum; -e -> -um; -u -> -uum.

Genitive examples: rosa -> rosae, rosarum; amico -> amici, amicorum; principe -> principis, principum; manu -> manui, manuum; re -> rei, rerum.