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

What Alzheimer’s blood tests currently measure Measuring levels of both amyloid and tau is key to understanding and diagnosing Alzheimer’s and other forms of dementia. —Sandee Lamotte, CNN Money, 7 Apr. 2025

Bateman and his team had been studying tau tangles, the abnormal clumps of protein that form inside the neurons of people with Alzheimer's. —Jon Hamilton, NPR, 2 Apr. 2025

But even without an antibody treatment, our group has found that opening the blood-brain barrier with focused ultrasound alone induces an intrinsic immune response in the brain that reduces beta amyloid and tau. —Rachel Nuwer, Scientific American, 28 Mar. 2025

Anti-amyloid immunotherapies People with Alzheimer’s tend to have an abnormal buildup of two proteins in their brains: amyloid and tau. —Alisa Hrustic, SELF, 24 Mar. 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