1. a coin or bill worth one dollar
Usage: informal; chiefly North American
2. a gold coin formerly used in France, worth about 20 francs
Usage: historical
3. a lieutenant, especially in the military
Usage: informal; military slang

Examples

• He pulled out a louie to pay for his coffee.
• The museum displayed a rare louie from the reign of Louis XIV.
• The louie ordered the troops to advance.
• I need another louie to make twenty dollars.
• That old louie coin is worth a lot to collectors.