phi

noun
\ ˈfī How to pronounce phi (audio) \

Definition of phi

: the 21st letter of the Greek alphabet — see Alphabet Table

Examples of phi in a Sentence

Recent Examples on the Web This term is called the Euler phi function after its inventor, the 18th-century mathematician Leonhard Euler. Quanta Magazine, "New Proof Settles How to Approximate Numbers Like Pi," 14 Aug. 2019 Other things that have zero phi, according to Tononi, include collectives of sentient individuals, such as corporations or the United States. Jason Pontin, WIRED, "How Do You Know You Are Reading This?," 2 Apr. 2018 CLE +250 LAL +275 BOS +700 HOU/SAS +1000 MIN +1400 PHI +1600 MIA +2500 GSW +2800 — OddsShark (@OddsShark) August 17, 2017 3. Charles Curtis, USA TODAY, "Why the Cavaliers aren't trading LeBron James," 18 Aug. 2017 Phi, to put it in numbers, is: Phi = φ = 1.61803398874989484820458683436563811772… and so on. Curtis Silver, WIRED, "The Sound of Phi (the Golden Ratio)," 18 June 2012

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'phi.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

See More

First Known Use of phi

15th century, in the meaning defined above

History and Etymology for phi

Middle Greek, from Greek phei

Keep scrolling for more

Learn More about phi

Time Traveler for phi

Time Traveler

The first known use of phi was in the 15th century

See more words from the same century

Statistics for phi

Cite this Entry

“Phi.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/phi. Accessed 3 Mar. 2021.

Style: MLA
MLA Chicago APA Merriam-Webster

More from Merriam-Webster on phi

Britannica.com: Encyclopedia article about phi

Comments on phi

What made you want to look up phi? Please tell us where you read or heard it (including the quote, if possible).

WORD OF THE DAY

Test Your Vocabulary

February 2021 Words of the Day Quiz

  • squirrel in winter
  • Which is a synonym of perdure?
Name That Thing

Test your visual vocabulary with our 10-question challenge!

TAKE THE QUIZ
 AlphaBear 2

Spell words. Make bears.

TAKE THE QUIZ
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!