heat

Concise Oxford English Dictionary © 2008 Oxford University Press:
heat/hiːt/

▶noun

• 1 the quality of being hot; high temperature.

  ■ Physics heat seen as a form of energy arising from the random motion of the molecules of bodies.

  ■ technical the amount of heat needed for or evolved in a specific process.

  ■ a source or level of heat for cooking.

• 2 intensity of feeling, especially of anger or excitement.

  ■ (the heat) informal intensive and unwelcome pressure.

• 3 a preliminary round in a race or contest.

▶verb

• 1 make or become hot or warm.

• 2 (heat up) become more intense and exciting.

  ■ (as adj. heated) inflamed with passion or conviction: a heated argument.

  ■ archaic inflame; excite.

– phrases
in the heat of the moment while temporarily angry or excited and without stopping to think.
on (or N. Amer. in) heat (of a female mammal) in the receptive period of the sexual cycle; in oestrus.

– derivatives
heatedly adverb.

– origin OE hǣtu (n.), hǣtan (v.), of Gmc origin; rel. to hot.