Defn: A genus of wading birds comprising the wood ibises. Tantalus's cup (Physics), a philosophical toy, consisting of a cup, within which is the figure of a man, and within the figure a siphon, the longer arm of which passes down through the bottom of the cup, and allows the escape of any liquid that may be poured in, when it reaches as high as the bend of the siphon, which is just below the level of the mouth of the figure in the cup.

TANTAMOUNT
Tan"ta*mount`, a. Etym: [F. tant so much (L. tantus) + E. amount.]

Defn: Equivalent in value, signification, or effect.
A usage nearly tantamount to constitutional right. Hallam.
The certainty that delay, under these circumstances, was tantamount
to ruin. De Quincey.

TANTAMOUNT
Tan"ta*mount`, v. i.

Defn: To be tantamount or equivalent; to amount. [Obs.] Jer. Taylor.

TANTIVY
Tan*tiv"y, adv. Etym: [Said to be from the note of a hunting horn.]

Defn: Swiftly; speedily; rapidly; — a fox-hunting term; as, to ride tantivy.

TANTIVY
Tan*tiv"y, n.

Defn: A rapid, violent gallop; an impetulous rush. Cleverland.

TANTIVY
Tan*tiv"y, v. i.