(uncountable) Thermal energy.

(uncountable) The condition or quality of being hot.

(uncountable) An attribute of a spice that causes a burning sensation in the mouth.

(uncountable) A period of intensity, particularly of emotion.

(uncountable) An undesirable amount of attention.

(countable, baseball) A fastball.

(uncountable) A noun "heat" represents a condition in which a mammal is sexually aroused or fertile and eager to mate, and in fandom slang, it refers to a cyclical period in omegaverse fiction where omegas have a strong biological urge to mate.

(countable) A preliminary race, used to determine the participants in a final race

(countable, by extension) A stage in a competition, not necessarily a sporting one; a round.

(countable) One cycle of bringing metal to maximum temperature and working it until it is too cool to work further.

(countable) A hot spell.

(uncountable) Heating system; a system that raises the temperature of a room or building.

(uncountable) The output of a heating system.

(countable) A violent action unintermitted; a single effort.

(uncountable, slang) The police.

(uncountable, slang) One or more firearms.

(uncountable, slang) Stylish and valuable sneakers.

(professional wrestling slang) To get a negative reaction from the audience, especially as a heel (or bad character).

(transitive) To cause an increase in temperature of (an object or space); to cause to become hot .

(intransitive) To become hotter.

(transitive, figurative) To excite or make hot by action or emotion; to make feverish.

(transitive, figurative) To excite ardour in; to rouse to action; to excite to excess; to inflame, as the passions.

(transitive, slang) To arouse, to excite (sexually).