A watch with other functions besides timekeeping. For example, a chronograph is a watch complication. Other complications coveted by watch collectors include: minute repeater, tourbillon, perpetual calendar, or slpit second chronograph.
an additional mechanism in a timepiece that already tells the hours, seconds, and minutes
Highly prized and almost always a signal of a complex, expensive movement, a complication refers to an additional mechanism(s) in a watch movement. Examples of complications include chronographs, perpetual calendars, and moon phase displays.