Tau \Tau\ (tou), n. [Gr. tay^.]

The nineteenth letter ([Tau], [tau]) of the Greek alphabet, equivalent to English t.

Source: Webster's Revised Unabridged Dictionary (1913)
 

Tau \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.

Source: Webster's Revised Unabridged Dictionary (1913)