‘Stimuluses’ or ‘Stimuli’: What is the Plural of Stimulus?

By Amy Gilmore, updated on May 5, 2023

Are you stuck on whether the plural form of 'stimulus' is 'stimuluses' or 'stimuli?' Do not worry. Many people are unsure of the correct plural form of this and other confusing words in the English language. However, you will not doubt the proper plural form after reading this guide.

Do you need a quick answer? 

Here it is: 

  •  'Stimuluses' is a misspelling. 
  • 'Stimuli' is the correct plural form of the word stimulus. 

If you want to discover why 'stimuli' is correct, read the rest of this guide. It contains example sentences, definitions, similar words, and usage tips to ensure you know how to use the word grammatically.

Which is the Plural Form of Stimulus: 'Stimuluses' or 'Stimuli?'

When talking about more than one stimulus, the correct form of the word is 'stimuli.' 'Stimuluses' is a misspelling and is never grammatically correct. This isn't very clear because you add -es to the end of some words that end in -us to create the plural form.

However, some words in the language derived from Latin follow a different rule. These words replace the -us suffix with an 'i.'

For example:

  • Octopus/octopi
  • Alumnus/alumni
  • Nucleus/nuclei
  • Fungus/fungi
  • Hippopotamus/hippopotami
  • Radius/radii

When to Use 'Stimuluses' or 'Stimuli'

As I mentioned, you should never use 'stimuluses.'

But how do you know when to use 'stimuli?'

  • Use 'stimuli' when you are talking about more than one stimulus.

For example, I might say something like:

I felt so overwhelmed by all of the stimuli around me. There were several loud sounds, as well as bright flashing lights. 

How Do You Use 'Stimuli' Correctly?

You should only use 'stimuli' when you need the plural form of 'stimulus' or something that creates a biological response to something internal or external.

For example:

  • We like to go to new places, but sometimes sensory experiences with many 'stimuli' overwhelm Mary.

Economic Stimulus

If you were talking about stimulus payments, you would use the singular version because the payments resulted from the same stimulus or event.

For example:

  • Have you received all of your stimulus payments?

The word stimulus is often used about the economy. An economic stimulus is a regulatory or government policy intended to stimulate the economy. Generally, when people speak about the economy, they use stimulus instead of 'stimuli.'

For example:

  • Financial stimulus
  • Stimulus payment
  • Stimulus package
  • Stimulus plan
  • Economic stimulus
  • Stimulus policies

Other Uses of 'Stimuli'

There are certain terms that people frequently use in connection to specific subjects. A 'stimuli' can be internal, like hormones produced in the body. Or, they can be external, like cold temperatures, sounds, vibrations, etc.

Typically, people use the word 'stimuli' when speaking about sensory objects or something that naturally produces a physical response. When speaking about stimulatory drugs, the correct word is stimulants.

Definition of 'Stimuli': What Does 'Stimuli' Mean?

According to the Merriam-Webster dictionary, 'stimuli' is the plural form of the noun stimulus, and it means:

  • Something that incites activity

It can also mean:

  • An incentive
  • A stimulant
  • An agent that causes a change in the body of a living organism

Related Words

There are quite a few words that relate to 'stimuli,' including:

  • Stimulation
  • Stimulated
  • Stimulation
  • Stimulus
  • Stimulate
  • Stimulates
  • Stimulator
  • Stimulatory
  • Stimulant
  • Stimulants


There are several synonyms that you can use instead of 'stimuli,' like:

  • Incentives
  • Encouragements
  • Motivations
  • Boosts
  • Impulses
  • Provocations
  • Instigations
  • Sticks
  • Pricks
  • Prods
  • Pokes

Origin of the Word 'Stimuli'

'Stimuli' comes from the Latin word stimulus, the word used for a cattle prod or a stick to keep cattle moving. The first examples of the word in texts appeared in the late 1600s. During the 1700s, the term was used in the context of medicine or responses in the body.

For example:

  • Researchers have been studying the long-term effects of 'stimuli' on the human brain.

Pronunciation of 'Stimuli'

Now that you know the correct version of stimulus, you need to know how to pronounce it.

Here is a quick guide: 

You can use this phonetic spelling to pronounce 'stimuli' correctly:


Examples of 'Stimuli' Used in a Sentence

Now that you know whether the plural form of stimulus is 'stimuluses' or 'stimuli,' let's look at some sample sentences to ensure you know how to use it correctly.

  • Stimuli can be lights, sounds, vibrations, medications, or anything else that causes a change in your body, mood, or perception.
  • Do you get overwhelmed by many stimuli?
  • We suggest the sensory deprivation event for people significantly impacted by all the stimuli.
  • Some people are more sensitive to external stimuli than others.
  • With all the stimuli in here, I do not know how you get anything done.
  • The hotel room overlooking the busy street was not peaceful. People were screaming, and there were a bunch of other stimuli, including sirens, flashing lights, and screeching tires.
  • With so many stimuli, how do you avoid getting overstimulated?
  • A research study found that some people are more productive when they listen to brown noise, but their productivity declines in the presence of other stimuli.
  • The stimulants can intensify the effects of stimuli.
  • The 3D theater combines, is an immersive experience that incorporates different types of stimuli into the show.
  • Going to the amusement park is a thrilling experience. There are many different stimuli, including intoxicating smells, rides that take your breath away, and popular music on the loudspeakers.
  • Using writing as meditation is a great way to calm yourself when you are overwhelmed by stimuli.

Final Advice on Whether the Plural Form of Stimulus is 'Stimuluses' or 'Stimuli'

You should know whether the plural form of stimulus is 'stimuluses' or 'stimuli' by now. However, here is a quick recap:

  • 'Stimuluses' is a misspelling. 
  • 'Stimuli' is the plural form of the noun 'stimulus.' 

You also learned that people typically do not use 'stimuli' when discussing the economy, stimulus payments, or stimulating medications.

If you get mixed up in the future, come back here to review. You can also look at the other guides in the confusing words section for help learning about other words and terms that trip up many people learning English. You can also benefit from reviewing the other posts as an aspiring writer.

Reading through a post or two each day will help you expand your vocabulary and learn how to properly use many terms so that you can write more confidently.

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Written By:
Amy Gilmore
Amy Gilmore is one of the lead freelance writers for WritingTips.org. She has been a professional writer and editor for the past eight years. She developed a love of language arts and literature in school and decided to become a professional freelance writer after a demanding career in real estate. Amy is constantly learning to become a better writer and loves sharing tips with other writers who want to do the same.

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