sweltering adjective 1noun 1forms 1 adjective1 •hot and humid; oppressively stickyThe day was sweltering, so Lauren put on the shortest pair of shorts she could find and went to get ice-cream with her friend Rob. noun1 •The situation of being or feeling hot and humid.March 11 1932, Northrop Frye, notebook It is truly a long way from Augustine's ultra-violet perspicacity to our swelterings in the intolerably sapping infra-red, but we are constantly plunging into deeper and deeper black and may rest our eyes in peace sometime. formsswelterings