Tau

сокращение от thousand astronomical units тысяча астрономических единиц

Англо-русский политехнический словарь

Tau

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

Merriam-Webster's Collegiate Dictionary

Tau

The mathematical constant that is the circumference of a circle divided by its radius, equal to twice pi. Some have suggested that pi is the wrong choice of constant to describe the geometry of circles etc. and tau = 2*pi would have been better. Most practising mathematicians think this is silly.

Free Online Dictionary of Computing