Swelter/ˈsweltər/ Definition 1 of 2Pro Tip 1/3Extreme Discomfort Indicates extreme discomfort due to high temperatures, more than just feeling hot. After the air conditioning broke, we sweltered through the night. Pro Tip 2/3Active Verb 'Swelter' is an active verb, often describing the action of someone suffering from the heat. They sweltered at the beach without an umbrella. Pro Tip 3/3Specific Contexts Best used in contexts where extreme heat is a key aspect, not just warm weather. The athletes sweltered during the desert marathon.