n. The use of only one metal (such as gold or silver) in the standard currency of a country, or as a standard of monetary value.
the GNU version of the Collaborative International Dictionary of English
n. The legalized use of one metal only, as gold, or silver, in the standard currency of a country, or as a standard of money values. See bimetallism.
The Century Dictionary and Cyclopedia
n. The use of only one metal as a standard of value in the coinage of a country; also, the economic theory that advocates such a single standard. See bimetallism.
Word Usage
"The United States effectively put gold on top in 1834, although British-style monometallism was not wholly adopted until 1900."