A plural noun indicates that there is more than one of that noun (while a singular noun indicates that there is just one of the noun). Most plural forms are created by simply adding an -s or –es to the end of the singular word. For example, there’s one dog (singular), but three dogs (plural). However, English has both regular and irregular plural nouns. Regular plurals follow this rule (and other similar rules), but irregular plurals are, well, not regular and don’t follow a “standard” rule.

Let’s start with regular plurals: regular plural nouns use established patterns to indicate there is more than one of a thing.

Recognize nouns marked with plural form –s.

As was mentioned earlier, we add the plural suffix –s to most words:

• cat → cats
• bear → bears
• zebra → zebras

However, after sounds s, z, sh, ch, and j, we add the plural suffix –es:

• class → classes
• sash → sashes
• fox → foxes

Some words that end in z also double their ending consonant, like quizzes.

After the letter o.

We also add the plural suffix –es to most words that end in o:

• potato → potatoes
• hero → heroes
• mosquito → mosquitoes

However, when the words have a foreign origin (e.g.,Latin, Greek, Spanish), we  just add the plural suffix –s

• taco → tacos
• avocado → avocados
• maestro → maestros

After –y and –f, –fe

When a word ends in y and there is a consonant before y, we change the y to i and add –es.

• sky → skies
• candy → candies
• lady → ladies

However, if the y follows another vowel, you simply add an –s.

• alloy → alloys
• donkey → donkeys
• day → days

When a word ends in –f or –fe, we change the f to v and add –es.

• leaf → leaves
• life → lives
• calf → calves

However, if there are two terminal fs or if you still pronounce the f in the plural, then you simply add an –s:

• cliff → cliffs
• chief → chiefs
• reef → reefs