di·vid·er / diˈvīdər/ • n. 1. a person or thing that divides a whole into parts. ∎ an issue on which opinions are divided: the big divider was still nuclear weapons. ∎ (also room divider) a screen or piece of furniture that divides a room into two parts.2. (dividers) a measuring compass, esp. one with a screw for making fine adjustments.