Noun:
    <mor> == <root> <plural>
    <plural> == s
    <root> == <>.

Cat:
    <> == Noun
    <root> == cat.

Dog:
    <> == Noun
    <root> == dog.

Ox:
    <> == Noun
    <root> == ox
    <plural> == en.

Mouse:
    <> == Noun
    <root> == mouse
    <plural> == <> s.