What does "straight up" refer to when serving a drink?

When a drink is ordered "straight up," it means that the drink is poured directly into a glass without any ice. This term is commonly used in bartending to indicate that the drink should be chilled by shaking or stirring with ice, but then the ice should be strained out before serving, resulting in a smooth and cold beverage presented in a glass without any ice.

This distinction is important because many patrons may have specific preferences regarding their drinks, and understanding the terminology helps to properly fulfill those requests. "Straight up" is different from serving a drink "on the rocks," which would involve pouring the drink over ice instead of leaving it completely ice-free. Other options, like a highball glass or soda water, do not pertain to the definition of "straight up," making this answer the most accurate.