heat up

verb

heated up; heating up; heats up

1

: to become warm or hot

The morning started out cold but it heated up quickly.

2

: to become more active, intense, or angry

Their conversation started to heat up.

Competition between the two companies is heating up.

3

heat (something) up or heat up (something) : to cause (something) to become warm or hot

Could you heat up the vegetables, please?