Gold Bug is a term used to describe investor

Investor

An investor is a party that makes an investment into one or more categories of assets --- equity, debt securities, real estate, currency, commodity, derivatives such as put and call options, etc...

s who are very bullish on buying the commodity

Commodity

In economics, a commodity is the generic term for any marketable item produced to satisfy wants or needs. Economic commodities comprise goods and services....

 gold

Gold

Gold is a chemical element with the symbol Au and an atomic number of 79. Gold is a dense, soft, shiny, malleable and ductile metal. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. Chemically, gold is a...

 (XAU - ISO 4217

ISO 4217

ISO 4217 is a standard published by the International Standards Organization, which delineates currency designators, country codes , and references to minor units in three tables:* Table A.1 – Current currency & funds code list...

). It can also be used to refer to a person who opposes or criticizes the use of fiat currency and supports a return to the use of the Gold Standard

Gold standard

The gold standard is a monetary system in which the standard economic unit of account is a fixed mass of gold. There are distinct kinds of gold standard...

 or some other currency system based on the value of gold and other hard assets. A third use is to refer to someone who considers one commodity, usually gold, "the appropriate measure of wealth, regardless of the quantity of other goods and services that it can buy".

The term was popularized in the 1896 US Presidential Election, when William McKinley

William McKinley

William McKinley, Jr. was the 25th President of the United States . He is best known for winning fiercely fought elections, while supporting the gold standard and high tariffs; he succeeded in forging a Republican coalition that for the most part dominated national politics until the 1930s...

 supporters took to wearing gold lapel pins, gold neckties, and gold headbands in a demonstration of support for gold against the "silver menace

Bimetallism

In economics, bimetallism is a monetary standard in which the value of the monetary unit is defined as equivalent both to a certain quantity of gold and to a certain quantity of silver; such a system establishes a fixed rate of exchange between the two metals...

", though the term's original use may have been in Edgar Allan Poe

Edgar Allan Poe

Edgar Allan Poe was an American author, poet, editor and literary critic, considered part of the American Romantic Movement. Best known for his tales of mystery and the macabre, Poe was one of the earliest American practitioners of the short story and is considered the inventor of the detective...

's 1843 story "The Gold-Bug

The Gold-Bug

"The Gold-Bug" is a short story by Edgar Allan Poe. Set on Sullivan's Island, South Carolina, the plot follows William Legrand, who was recently bitten by a gold-colored bug. His servant Jupiter fears him to be going insane and goes to Legrand's friend, an unnamed narrator who agrees to visit his...

," about a cryptographic treasure map.