noun

• (numismatics) Official designation for currency in some parts of the world, including Canada, the United States, Australia, New Zealand, Singapore, Hong Kong, and elsewhere. Its symbol is $.
  "But poverty’s scourge is fiercest below $1.25 (the average of the 15 poorest countries’ own poverty lines, measured in 2005 dollars and adjusted for differences in purchasing power): people below that level live lives that are poor, nasty, brutish and short."
• (by extension) Money generally.
  "Television, a favored source of news and information, pulls the largest share of advertising monies. In 1935, newspapers received 45 percent of the advertising dollar, magazines 8 percent, and radio 7 percent."
• (by extension, Malaysia, colloquial) A ringgit, a unit of currency in Malaysia.
• (UK, colloquial, historical) A quarter of a pound or one crown, historically minted as a coin of approximately the same size and composition as a then-contemporary dollar coin of the United States, and worth slightly more.