'Tau' definitions:

Definition of 'tau'

From: WordNet
noun
The 19th letter of the Greek alphabet

Definition of 'Tau'

From: GCIDE
  • Tau \Tau\ (tou), n. [Gr. tay^.] The nineteenth letter ([Tau], [tau]) of the Greek alphabet, equivalent to English t. [Webster 1913 Suppl.]

Definition of 'Tau'

From: GCIDE
  • Tau \Tau\, n. [Gr. tay^ the letter [tau] (English T).] (Zool.) The common American toadfish; -- so called from a marking resembling the Greek letter tau ([tau]). [1913 Webster]
  • Tau cross. See Illust. 6, of Cross. [1913 Webster]