burn up phrasal verb ( see also ↑ burn )
1 . if something burns up or is burnt up, it is completely destroyed by fire or heat:
The satellite will burn up as it re-enters the Earth’s atmosphere.
burn something ↔ up
Most of the woodland has now been burnt up.
2 . burn something ↔ up informal to use a lot of something in a careless way:
Most household appliances burn up loads of electricity.
He just burns up money!
3 . be burning up spoken if someone is burning up, they are very hot, usually because they are ill:
Feel his forehead – he’s burning up.
4 . burn somebody up American English informal to make someone very angry:
The way he treats her really burns me up.
5 . burn something ↔ up to use energy that is stored in your body, by being physically active:
As we get older, our body becomes less efficient at burning up calories.