The letter Τ/τ in the Greek, Hebrew and ancient Semitic alphabets, being the nineteenth letter of the Classical and Modern Greek, the twenty-first letter of Old and Ancient Greek.
A Τ-shaped sign or structure; a St. Anthony's cross, sometimes considered as a sacred symbol.
(physics, dated) A tau meson, now usually known as a kaon.
(biology)Tau protein, a type of protein that stabilizes microtubules in the human central nervous system, failures of which are associated with forms of dementia.
