To heat something after it has cooled off, especially previously cooked food (also in figurative senses).
To become hot again after having cooled off (also in figurative senses).
An afterburner.
To heat or reheat (e.g. food).
To reach, or cause to reach, a normal operating temperature (of a car for example).
To become warmer.
To do gentle exercise, stretching etc., in order to prepare the body for more vigorous exercise.
To make (an audience) enthusiastic or animated before a show
To prepare for an activity by carrying out a practice or preparation routine.