\Tau\ (tou), n. [Gr. tay^.]
The nineteenth letter ([Tau], [tau]) of the Greek alphabet,
equivalent to English t.

\Tau\, n. [Gr. tay^ the letter [tau] (English {T}).]
(Zo["o]l.)
The common American toadfish; -- so called from a marking
resembling the Greek letter tau ([tau]).
{Tau cross}. See Illust. 6, of {Cross}.