theta

Borrowed from Ancient Greek θῆτα (thêta).

• (UK) IPA^(key): /ˈθiːtə/
• (US, Canada) IPA^(key): /ˈθeɪtə/, /ˈθitə/

• Audio (US):

  (file)

• (Hong Kong) IPA^(key): /ˈθeɪ.ta/, [fei̯˥ tʰaː˩]
• Rhymes: -iːtə, -eɪtə

theta (plural thetas)

1. The eighth letter of the Modern Greek alphabet, ninth in Old Greek: Θ, θ.
2. (mathematics) The measure of an angle.
3. (aviation, by extension) Pitch angle; the angle between an aircraft's longitudinal axis and the horizontal plane.

   Synonym: deck angle

4. (finance) The sensitivity of the value of a derivative with respect to time; the "time decay".
5. (biology) Designating a level of brain activity as measured by electroencephalography having a frequency of between four and seven cycles per second (associated with drowsiness in adults).
   • 2018 September 19, Meghan O'Gieblyn, “The Most Unread Book Ever Acclaimed”, in The Paris Review:

     The reader is less likely to throw the book down in a fit of disgust than she is to be lulled into a theta state, a highway hypnosis induced by page after page of incantatory prose.

6. (phonology) The voiceless dental fricative represented by θ.

• (measure of derivative price sensitivity): Greeks (includes list of coordinate terms)

(pitch angle of an aircraft):

• alpha
• beta
• gamma

• → Malay: teta

• (Greek-script letter names) alpha, beta, gamma, delta, epsilon, zeta, eta, theta, iota, kappa, lambda, mu, nu, xi, omicron, pi, rho, sigma, tau, upsilon, phi, chi, psi, omega

Borrowed from Ancient Greek θῆτα (thêta).

• IPA^(key): (Central, Balearic) [ˈtɛ.tə]
• IPA^(key): (Valencia) [ˈte.ta]

theta f (plural thetes)

1. theta; the Greek letter Θ (lowercase θ)

• “theta”, in Diccionari de la llengua catalana [Dictionary of the Catalan Language] (in Catalan), second edition, Institute of Catalan Studies [Catalan: Institut d'Estudis Catalans], April 2007
• “theta”, in Gran Diccionari de la Llengua Catalana, Grup Enciclopèdia Catalana, 2025
• “theta” in Diccionari normatiu valencià, Acadèmia Valenciana de la Llengua.

• théta

Borrowed from Ancient Greek θῆτα (thêta).

• IPA^(key): [ˈtxɛːta]
• IPA^(key): [ˈtɛːta]

theta n or f

1. theta (Greek letter)

when feminine:

Indeclinable when neuter.

From the Ancient Greek θῆτα (thêta).

• IPA^(key): /ˈtɛ.ta/^[1]
• Rhymes: -ɛta
• Hyphenation: thè‧ta

theta m or f (invariable)

1. theta (Greek letter)

theta

1. reliable
2. trustworthy

Learned borrowing from Ancient Greek θῆτα (thêta), from Phoenician 𐤈 (ṭ‬ /⁠ṭēt⁠/).

• IPA^(key): /ˈtɛ.ta/

• Audio:

  (file)

• Rhymes: -ɛta
• Syllabification: the‧ta

theta f

1. theta (Greek letter Θ, θ)

• theta in Polish dictionaries at PWN

theta f (plural thetas)

1. Pre-reform spelling (used until 1943 in Brazil and 1911 in Portugal) of teta.

Borrowed from Ancient Greek θῆτα (thêta).

• IPA^(key): /ˈteta/ [ˈt̪e.t̪a]
  • Rhymes: -eta
• IPA^(key): /ˈtita/ [ˈt̪i.t̪a]
  • Rhymes: -ita

theta f (plural thetas)

1. theta; the Greek letter Θ, θ

   Synonyms: zeta, tita