1. [for the weather or a person or something] to become warmer or hotter

1. I think it is going to warm up next week.

2. Wait for the oven to warm up before you put the food in.

2. Fig. [for someone] to become more friendly. (A warm person is a friendly person.)

1. Todd began to warm up halfway through the conference.

2. After he had worked there for a while, he began to warm up.

3. Fig. to prepare for some kind of performance or competition.

1. The team had to warm up before the game.

2. They have to warm up.