tau
tau
UK[tɔː]US[taʊ]
n
The 19th letter of the Greek alphabet (Τ, τ), corresponding to the English 't'.
n
A short name for the tau lepton, an elementary particle in physics.
n
A symbol (τ) used to represent various quantities, such as torque, shear stress, or the tau protein in neuroscience.
Etymology
The word 'tau' entered English in the 13th century as the name for the Greek letter Τ, τ, borrowed directly from the Greek 'ταῦ' (tau). The Greek letter name itself is of Semitic origin, derived from the Phoenician letter 'tāw', which meant 'mark' or 'sign'. The shape of the original Phoenician letter was a simple cross or mark, which evolved into the Greek 'T' shape. In modern scientific contexts, this ancient alphabetic name has been repurposed to denote specific concepts, such as a subatomic particle and mathematical constants, carrying forward its legacy as a fundamental symbol.
Analysis
This is a simplex word, a direct borrowing of the name of a Greek letter. It cannot be meaningfully segmented into smaller morphemes in English.
Examples
The lowercase tau resembles a cross with a curved top.
The discovery of the tau lepton was a significant milestone in particle physics.
In Alzheimer's disease research, the aggregation of tau protein is a key focus.