Irregular Plurals

Some nouns change their spelling when they become plural.

Child: children
Foot: feet
Goose: geese
Louse: lice
Man: men
Mouse: mice
Ox: oxen
Tooth: teeth
Woman: women

Some nouns have the same form whether they are singular or plural.

Deer: deer
Moose: moose
Portuguese: Portuguese
Series: series
Sheep: sheep
Species: species
Swine: swine

The only plurals formed with apostrophes are the plurals of numbers, letters, and words highlighted as words. Here are some examples:

How many 3’s make 9?
Be sure to mind your p’s and q’s.

Some words from other languages form plurals in other ways, often determined by the laws of the language of their origin. Here are some examples:

analysis: analyses
axis: axes
bacterium: bacteria
index: indices
parenthesis: parentheses