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

Diranersen is what’s called an antisense oligonucleotide that doesn't attack tau buildup but instead instructs a tau-producing gene to produce less. — ABC News, 14 July 2026

Diranersen is what’s called an antisense oligonucleotide that doesn’t attack tau buildup but instead instructs a tau-producing gene to produce less. — Lauran Neergaard, Fortune, 14 July 2026

In May, the company announced results from a mid-stage clinical trial investigating a treatment for Alzheimer’s disease called diranersen that targets the protein tau. — Adam Feuerstein, STAT, 1 July 2026

Cork recently led a meta-analysis of 30 studies investigating the effects of GLP-1s on Alzheimer’s pathology—namely the buildup of beta-amyloid and p-tau—to determine just that. — Jenna Anderson, Health, 2 June 2026

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