Plural of Cactus | Spelling & Examples

There are two plural forms of the word cactus, which are cacti, pronounced [kak-tahy], and cactuses, pronounced [kak-tuh-siz]. Both forms are widely accepted, but cacti tends to be more commonly used.

Cactuses or cacti?

Both cactuses and cacti are grammatically correct and widely accepted, but cacti is used more often.

Cacti follows Latin pluralization rules where nouns ending in “-us” are made plural by changing the ending to “-i” (e.g., fungus/fungi and radius/radii). Cactuses follows regular pluralization rules where you simply add “-s” or “-es” to a singular noun to make it plural.

Interestingly, Merriam-Webster lists “cactus” as the third choice for the plural of cactus after the more commonly used cacti and cactuses. However, it is preferable to use either cacti or cactuses to avoid unnecessary confusion.

What is an irregular plural noun?

Irregular plurals are nouns that don’t follow the regular rules of pluralization. To make a regular noun plural, you simply add “-s” or “-es” to the end of the singular form (e.g., window/windows and sandwich/sandwiches).

However, there are different rules of pluralization for irregular plural nouns. Latin-derived nouns, for example, change the “-us” at the end of the singular form to “-i” to form the plural (e.g., alumnus/alumni and stimulus/stimuli). Greek-derived singular nouns are made plural by changing the “-is” ending to “-es” or the “-on” ending to “-a” (e.g., axis/axes and criterion/criteria).

In the case of the word “cactus,” the plural form cacti is an irregular plural and cactuses is a regular plural. Both are correct and can be used interchangeably.

There are other irregular plurals that come from other origins, like Old English or other linguistic origins.

One type of irregular plural noun is called a zero plural, which is a word that remains the same in both the singular and plural forms.

Frequently asked questions about the word cactus

How do you spell cactus?

The word cactus is spelled C-A-C-T-U-S.

Cactus has two correct plural forms; one plural of cactus is spelled C-A-C-T-I, and the other plural version is spelled C-A-C-T-U-S-E-S.

Scribbr’s free Grammar Checker is perfect for ensuring everything is spelled correctly no matter what you’re writing.

What is a synonym for cactus?

The word cactus isn’t listed in the thesaurus, as it refers to a very specific type of plant.

However, some possible synonyms that refer to very similar types of plants are succulent, prickly pear, and yucca.

Scribbr’s free Paraphrasing Tool can help you easily find the right synonyms for the words in your writing.