Tau Day

proper noun

June 28th, an annual celebration of the mathematical constant 𝜏 (tau).

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Meanings

proper noun
  1. June 28th, an annual celebration of the mathematical constant 𝜏 (tau).

    So here's to June 28th β€” Tau Day.

    2018 March 14, Emily Conover, Forget Pi Day. We should be celebrating Tau Day
    2 more examples

    But all isn’t lost for those looking for a fun day to celebrate math: Tau Day (6/28, or June 28th) is today!

    2019 June 28, Chaim Gartenberg, Tau Day is here: celebrate tau, not pi, as the true circle

    Tau Day is a time to celebrate and rejoice in all things mathematical.

    2010 June 28, Michael Harti, The Tau Manifesto

Origin

By analogy with Pi Day, with 𝜏 (tau) being equivalent to 2Ο€ (6.28...)

Full word history & related roots β†’
Cite this entry
APA

Tau Day. (n.d.). In WatkinsX Dictionary. Retrieved November 4, 2026, from https://dictionary.watkinsx.com/word/Tau%20Day

MLA

β€œTau Day.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/Tau%20Day. Accessed November 4, 2026.

Chicago

WatkinsX Dictionary, s.v. β€œTau Day,” accessed November 4, 2026, https://dictionary.watkinsx.com/word/Tau%20Day.

Source: Tau Day on Wiktionary, CC BY-SA 4.0.