What does tau mean?
Tau is most commonly the name of τ, the nineteenth letter of the Greek alphabet. In physics, tau may also mean a short-lived elementary subatomic particle whose decay has helped researchers investigate the Higgs boson; the particle was once nicknamed the "ghost particle" because it left only a fleeting trace in detectors. In biology and medicine, tau refers to a family of proteins associated with microtubules, structures that help maintain the internal framework of nerve cells. Abnormal accumulation and modification of these proteins are associated with several neurodegenerative diseases, including certain forms of dementia. Outside these technical contexts, tau usually remains a reference to the Greek letter. Its pronunciation differs noticeably between American and British English, and the word is useful for recognizing Greek inscriptions as well as for understanding terminology in particle physics, neuroscience, and medicine.
nounTau is the Greek letter τ, the nineteenth letter of the Greek alphabet. The word also denotes an elementary subatomic particle and the microtubule-associated proteins that help maintain the structure of nerve cells.
- The Greek letter τ, the nineteenth letter of the Greek alphabet.
- A symbol τ used in physics for quantities such as a time constant or relaxation time.
- An elementary subatomic particle, now observed experimentally, that decays into other particles.
- A family of microtubule-associated proteins that stabilize neuronal structures; abnormal accumulation of these proteins is associated with several neurodegenerative diseases.
"The museum's curator identified the symbol as a tau, the nineteenth letter of the Greek alphabet."
"The inscription contains a clear tau followed by several letters that are too worn to read."
"Researchers used a sensitive imaging technique to detect abnormal tau deposits in the patient's brain."
Separate particles or letter forms may be called taus, although "tau particles" is more usual in scientific prose. Tau proteins are normally referred to individually or collectively without taking a simple plural.
"The detector recorded two taus before they decayed."
The elusive particle that helped scientists study the Higgs boson was nicknamed the "ghost particle."
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does tau come from?
Tau is the English name of the Greek letter ταῦ (tau), adopted into the Greek alphabet from the Phoenician writing system. Its form ultimately derives from the Phoenician letter called taw, whose design was based on a cross-like mark. Related letter names, including Hebrew tav and Arabic tāʾ, continue to be used in their respective alphabets.
How tau is actually used
The usual American pronunciation is /taʊ/, while British English commonly uses /tɔː/. The particle and protein senses belong to specialist scientific and medical contexts, whereas the Greek-letter sense is general and educational.
Easily confused with tau
Taw may name the Hebrew letter tav or mean a mark or sign, whereas tau is the Greek letter τ and is also used in particle physics and neurobiology.