Of a person: feeling uncomfortably hot.
Of a thing: extremely hot or active.
Of the weather: very hot.
That boils or boil.
Extremely
An animation style with constantly changing wavy outlines, giving a shimmering or wobbling appearance.
The process of changing the state of a substance from liquid to gas by heating it to its boiling point.
The heat was stifling; it seemed hard to breathe and the exertion of rolling over on the bed seemed too much.
That stifles.
The act by which something is stifled.