I know how to pronounce the first symbol as "theta", but the other symbol that looks like a circle with a vertical slash, I don't know what to call it.

I would appreciate any help. Thank you

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3 Answers 3


That's lowercase Greek phi, pronounced with an initial f sound and rhyming with English pie, lie or sky. That said, some speakers may pronounce it rhyming with English see, key or me.

See https://en.m.wikipedia.org/wiki/Phi for more details.

  • 6
    $\begingroup$ On the pronunciation: As mentioned in the wikipedia article, the rhymes-with-pie version corresponds to Ancient Greek, while the rhymes-with-see version corresponds to Modern Greek. There is a similar ancient/modern pronunciation difference for $\pi$. $\endgroup$
    – Adam
    Commented May 6 at 12:56
  • $\begingroup$ Nowadays, who knows how to pronounce $\chi$ or $\xi$? $\endgroup$ Commented May 6 at 18:00
  • $\begingroup$ @GeraldEdgar: $\xi$ is pronounced "xi" [ksi], the other one ($\chi$) is pronounced as "chi" but as in Dutch or German, I don't know if there are English words with that consonant. $\endgroup$
    – Dominique
    Commented May 7 at 6:16
  • $\begingroup$ The Modern Greek names for $\beta$ and $\delta$ are ['vi:ta] and [ˈðelta], but that is not relevant to an English-language mathematical context, where we use ['bi:tə] and ['dɛltə], even though these are different from how Greeks would pronounce them. The point is that the English-language pronunciation of a word might be different from its pronunciation in the language it was borrowed from. $\endgroup$
    – Rosie F
    Commented Jun 6 at 8:54

Please check the entire Greek alphabet, as you can find it in this Wikipedia page: https://en.wikipedia.org/wiki/Greek_alphabet.

I must add that there are two ways to write the letter $phi$ in MathJax (or LaTeX):

  • The normal way: $\text{phi} = \phi$
  • The "var" way: $\text{varphi} = \varphi$
  • 2
    $\begingroup$ Interestingly, the "var" or variant form is actually more common in some parts of the world or in certain contexts. $\endgroup$
    – J W
    Commented May 6 at 11:13
  • 2
    $\begingroup$ @JW: I confirm: I've followed a year of Ancient Greek in my secondary school (in Belgium), and there we learnt to write "phi" in the way it's here known as "varphi". $\endgroup$
    – Dominique
    Commented May 6 at 11:16
  • 1
    $\begingroup$ The "varphi" style is what's generally used in handwritten mathematical context, while the other is a more block typographic style. Which is used in typeset papers is usually a matter of the author's (or in some cases editor's?) preference. In a worst case they may use both with different meanings... $\endgroup$ Commented May 6 at 17:27
  • 2
    $\begingroup$ @R..GitHubSTOPHELPINGICE The ‘varphi’ style is also the traditional Greek miniscule form used in almost all handwriting that doesn’t involve intentional use of block letters, it’s not really specific to mathematics in any way. $\endgroup$ Commented May 6 at 17:29
  • 1
    $\begingroup$ Strictly speaking, there are three since $\Phi$ (\Phi) is also "phi". $\endgroup$
    – Pedro
    Commented May 6 at 21:37

For such a query, you might find it quicker to use one of the following tools:

  1. Google Image Reverse Search: Navigate to google.com and upload an image of the symbol. Google will display similar images and web pages that feature these images. By examining these, you can find the name of the symbol.

  2. Detexify: Visit Detexify and draw the symbol. The website will provide you with the LaTeX command for the symbol, which usually corresponds to its name.

  3. Chat Bots: ChatGPT can definitely recognize symbols. Other alternatives include Claude and Gemini by Google.


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