This noun describes intense, burning heat, particularly from the sun. In Revelation, it appears in contexts of divine judgment and protection: the redeemed will not be struck by scorching heat (7:16), while the wicked are scorched by great heat as a plague (16:9). The classical usage extended to fever heat and even frost in plural form, but the NT uses focus exclusively on solar or supernatural heat as an instrument of suffering. All target languages use straightforward terms for heat without distinguishing between natural and judgment-heat, suggesting the word itself is neutral regarding source.