The currency unit of the United States, comprised of 100 cents. Traders shorten it to USD. The U.S. dollar is the worldÂ’s most frequently used currency in business transactions. Even transactions not involving a U.S. party often are cited in dollars. The dollar is also the name for the currency unit of Antigua, Australia, Bahamas, Barbados, Belize, Brunei, Canada, Dominica, Fiji, Grenada, Guyana, Hong Kong, Jamaica, Liberia, Marshall Islands, Micronesia, Namibia, Nauru, New Zealand, Palau, Saint Kitts and Nevis, Saint Lucia, Saint Vincent and the Grenadines, Singapore, Solomon Islands, Taiwan, Turk and Caicos, Trinidad and Tobago, Tuvalu, and Zimbabwe.