Changing the central vowel(s)

For some nouns, the plural is formed by changing the vowel in the middle. We will look at some of these nouns below.

Nouns with ‘oo’ and ‘ou’ in the middle:

Nouns with ‘oo’ in the middle generally form their plural by changing ‘oo’ to ‘ee’.

Nouns with ‘ou’ in the middle form their plural by changing ‘ou' to ‘i’. For these nouns (ou nouns), the ‘s’ following the ‘ou’ is changed to ‘c’.

For example to form the plural of mouse, we change ‘ous’ to ‘ic’ to make mice.

Mouse -> Mouse + ic -> Mice

Example:

Foot --------------------> Feet

    (Plural)

Tooth --------------------> Teeth

     (Plural)

Mouse --------------------> Mice

       (Plural)

Louse ----------------------------------> Lice

        (Plural)

Note: this is not true for all nouns with ‘oo’ in the middle. For example, the plural of book is books and NOT beek. Also, the plural of room is rooms and NOT reem.

Similarly, not all nouns with ‘ou’ in the middle form their plural by changing ‘ou’ to ‘i’. For example, the plural of house is houses and NOT hice. The plural blouse is blouses NOT blice.