Phenomenon vs. Phenomena: What’s the Difference?

Phenomena are plural. A phenomenon is singular. 

Sounds simple enough. 

What makes this set of words particularly confusing is that so many people use the plural form to describe a single phenomenon. Merram-Webster explains that they aren’t totally incorrect to do so. There’s some precedent:

“It is etymologically no more irregular than stamina and agenda, but it has nowhere near the frequency of use that they have, and while they are standard, phenomena is still rather borderline.”

So, while you could use “phenomena” in both instances and get away with it, we urge you to keep your Latinate plurals neat and tidy. 

One datum. Two data. 

One criterion. Two criteria.

One stratum. Two strata. 

One phenomenon. Two phenomena.

Many people view the singular phenomena as a mistake. While you may be able to justify your choice—What about agenda?!—you can’t take back a bad first impression. Stick to standard English usage, which requires the -non ending for the singular.

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According to the Online Etymology Dictionary, the word phenomenon originated with the Proto-Indo-European (PIE) root bha-, meaning “to shine.” The Greek word phainein, to “bring to light, cause to appear, show,” developed from that PIE root. The passive form, phainesthai, meant “to appear.” From the neuter present participle of phainesthai, we get the noun form, phainomenon. Already, the Greek phainomenon resembled our modern word “phenomenon”. By Late Latin, the spelling phænomenon emerged. In the 1570’s, the word made its way into the English language, referring to “a fact directly observed, a thing that appears or is perceived, an occurrence.” 

As a word borrowed directly from Latin, the singular form phenomenon retained the plural phenomena. The Online Etymology Dictionary explains that an -a is “the nominative neuter plural ending of certain nouns and adjectives in Latin and Greek that have been adopted into English.”

Immanuel Kant and Phenomena

Immanuel Kant’s work in philosophy had a large impact on how we understand phenomena today. He provided definitions for both noumena and phenomena. According to the Encyclopaedia Britannica, Kant described a noumenon as, “the thing-in-itself (das Ding an sich) as opposed to what Kant called the phenomenon—the thing as it appears to an observer.” He used this terminology to distinguish between speculative reason and practical (or moral) reason. Kant contended that “the phenomenal world is an expression of power and that the source from which this power comes can only be the noumenal world beyond.” 

Kant outlined the differences between a noumenon and a phenomenon in The Critique of Pure Reason (1781). The Online Etymology Dictionary confirms that the definition of phenomenon meaning “an appearance or immediate object of experience” comes from the period directly after the publication of that book. The new definition of phenomena made its way into popular usage by 1788. 


Interestingly, Merriam-Webster lists some definitions of phenomenon as having the plural “phenomena” and others as having the plural “phenomenons”.

Specifically, the definition “an exceptional, unusual, or abnormal person, thing, or occurrence” pluralizes to “phenomenons”.

Otherwise, the following definitions of phenomenon have “phenomena” as the plural:

  • an observable fact or event
  • an object or aspect known through the senses rather than by thought or intuition
  • a temporal or spatiotemporal object of sensory experience as distinguished from a noumenon
  • a fact or event of scientific interest susceptible to scientific description and explanation

Merriam-Webster does not indicate a preferred plural for this definition: “a rare or significant fact or event.” So, presumably, both plurals can be used. When the word refers to the unusual or rare, you can use “phenomenons”; however, scientific or sensory observations should always be pluralized to “phenomena”. 


According to, synonyms for phenomenon include:

  • anomaly
  • aspect
  • circumstance
  • episode
  • event
  • experience
  • fact
  • incident
  • miracle
  • paradox
  • reality
  • sensation lists the following as synonyms for phenomena:

  • development
  • experience
  • phantasm
  • wonder
  • phenomenality


According to, antonyms for phenomenon include:

  • usualness
  • normality
  • regularity

The Words in Context

“‘What’s it called? Synesthesia?’ She asks her son. She’s still learning about the neurological phenomenon which is often described as a ‘crossing of the senses.'”
Good Morning Tampa Bay, “Local Musical Prodigy Amazes Listeners…”

“Scientists have observed similar phenomena closer to home, around Earth and our planetary neighbors, but never in interstellar space.” 
The Atlantic, “The Voyagers Found a Small Surprise in Interstellar Space”

“In 1968 Sonfist wrote: ‘As in war monuments that record the life and death of soldiers, the life and death of natural phenomena such as rivers, springs, and natural outcroppings need to be remembered.'”
Vanity Fair, “Green River Project’s New Furniture Collection…”

“The phenomenon is called a ‘great conjunction’—when astronomical objects appear to meet up with each other from Earth’s vantage point.”
Time Out New York, “Jupiter and Saturn’s Great Conjunction Will Be Visible…”

“Recent increases in fertility in some of the richest nations are an interesting phenomenon.”
The Economist, “Fertility, illustrated”

“One big phenomenon during the pandemic of 2020 has been the rise in digital audio as millions of listeners of all ages turn to online music and podcasts to get them through their darkest times.”
CNBC, “How Spotify Hopes to Win the Podcasting Wars”