tau

noun

ˈtau̇  ˈtȯ 

1

: the 19th letter of the Greek alphabet see Alphabet Table

2

: a short-lived elementary particle of the lepton family that exists in positive and negative charge states and has a mass about 3500 times greater than an electron

called also tau particle

3

: a protein that binds to and regulates the assembly and stability of neuronal microtubules and that is found in an abnormal form as the major component of neurofibrillary tangles

Examples of tau in a Sentence

Recent Examples on the Web

An experimental drug in phase 2 clinical trials uses a new approach to reduce the accumulation of tau. —Juergen Eckhardt, Forbes.com, 22 July 2025

By learning from the natural tau regulation seen in newborns, researchers may discover new ways to prevent or treat Alzheimer’s disease by avoiding the pathological buildup of tau seen in aging brains. —New Atlas, 30 June 2025

Both former heavy drinkers and heavy drinkers also had higher odds of developing tau tangles, an Alzheimer’s biomarker.5 Why Does Drinking Make the Brain More Prone to Injury? —Cathy Nelson, Health, 7 May 2025

The scientists looked for signs of brain injury, including tau tangles (abnormal accumulations of protein linked to Alzheimer’s disease) and hyaline arteriolosclerosis (a condition that causes small blood vessels to narrow and become thick and stiff). —Tom Gavin, EverydayHealth.com, 10 Apr. 2025

Word History

Etymology

Middle English taw, from Latin tau, from Greek, of Semitic origin; akin to Hebrew tāw taw

First Known Use

14th century, in the meaning defined at sense 1

Phrases Containing tau

• tau cross

Kids Definition

tau

noun

ˈtau̇ 

ˈtȯ

: the 19th letter of the Greek alphabet

—Τ or τ

Medical Definition

tau

noun

ˈtau̇  ˈtȯ 

: a protein that binds to and regulates the assembly and stability of neuronal microtubules and that is found in an abnormal form as the major component of neurofibrillary tangles

called also tau protein