(with up) To heat; to make or become hot.

(with up) To become lively or exciting.

(of an object) Having a high temperature.

“He forgot that the frying pan was hot and burned his hand.”

(of the weather) Causing the air to be hot.

“It is hotter in summer than in winter.”

(of a person or animal) Feeling the sensation of heat, especially to the point of discomfort.

“Aren't you hot with that thick coat on?”