1. a person who is eating a meal, especially at a restaurant
2. a small, informal restaurant, typically serving simple American food

Examples

• The waiter served coffee to every diner in the restaurant.
• Late-night diners filled the 24-hour restaurant.
• We stopped at a roadside diner for breakfast.
• The chrome diner had red vinyl booths and a long counter.
• The diner ordered the daily special.
• That old diner serves the best pie in town.
• Several diners complained about the slow service.