Row, Row, Row Your Noun
-us, -um, -ī, -ō, –ō,
-ī, -ōs, -ōrum, -īs, -īs,
Second declension masculine: my equus is deceased!

-r, -um, -ī, -ō, –ō,
-ī, -ōs, -ōrum, -īs, -īs
Second declension -r masculine: this liber has a crease!

-um, -um, -ī, -ō, -ō,
-a, -a, -ōrum, -īs, -īs,
Second declension neuter: this verbum is from Greece!