Diner/ˈdaɪnər/ Definition 1 of 2Pro Tip 1/3Eating Context Use 'diner' to refer to someone who is actively eating, not just present in a restaurant. The diners at table four ordered the chef's special. Pro Tip 2/3Not Always Customers 'Diner' can refer to anyone eating, not necessarily a paying customer. Family members at a reunion could be referred to as diners. Pro Tip 3/3Social Setting 'Diner' often implies a social experience, like dining out with friends or family. The diners were laughing and sharing stories over dinner.