swelter

Etymology

From Middle English swelteren, frequentative form of Middle English swelten (“to die; faint”), from Old English sweltan (“to die”), from Proto-West Germanic *sweltan, from Proto-Germanic *sweltaną (“to die”), from Proto-Indo-European *swel- (“to smolder; burn”), equivalent to swelt + -er (frequentative suffix). More at swelt.

verb

1. (intransitive) To suffer terribly from intense heat.
2. (intransitive) To perspire greatly from heat.
3. (transitive) To cause to faint, to overpower, as with heat.
   It was so rare a piece of fun To see the swelter'd cattle run 1796, Samuel Taylor Coleridge, Fire, Famine, and Slaughter

noun

1. Intense heat.
   The summer swelter did not relent until late in September, most years.