$ DOLLAR $

“A weight of gold or silver” Encyclopedia Britannica, 1962.

“412.5 grains of silver” World Dictionary, 1959.

The Century Dictionary, Published 1914 (with over 8,000 pages of definitions) defines the term DOLLAR as “The monetary unit or standard of value of the United States and Canada. By the term Dollar in the United States is intended the coined dollar of the United States, a certain quantity in weight and fineness of gold or silver…”Silver Certificates state the following: “This certifies that there is on deposit in the Treasury of the United States of America (denomination) Dollar(s) in silver payable to the bearer on demand.”

United States Notes states the following:

“The United States of America will pay to the bearer on demand (denomination) Dollar(s).”

A NOTE cannot be a DOLLAR, it can only be a promise to pay.
http://www.urbandictionary.com/define.php?term=dollar


http://mises.org/rothbard/genuine.asp
The definition must be real and effective rather than nominal. Thus, the U.S. statutes define the dollar as 1/42.22 gold ounce, but this definition is a mere formalistic accounting device. To be real, the definition of the dollar as a unit of weight of gold must imply that the dollar is interchangeable and therefore redeemable by its issuer in that weight, that the dollar is a demand claim for that weight in gold.

This Weight of Measurement was Removed, When the Gold Standard was Replaced with Fiat money, The name was kept $ DOLLAR $ but the paper is not backed by anything, Illusionary Value.... Are you In-Spelled in the Weavers Web? Trust the System-Matrix ?

Today, like the currency of most nations, the dollar is fiat money, unbacked by any physical asset.
http://en.wikipedia.org/wiki/History_of_the_United_States_dollar#Fiat_standard

Fiat money is money that has value only because of government regulation or law. The term derives from the Latin fiat, meaning "let it be done", as such money is established by government decree. Where fiat money is used as currency, the term fiat currency is used. Today, most national currencies are fiat currencies, including the US dollar, the euro, and all other reserve currencies, and have been since the Nixon Shock of 1971.
http://en.wikipedia.org/wiki/Fiat_money