The phrasal verb 'heat up' is predominantly used in informal speech, often found in casual conversations and informal writing. It generally refers to increasing the temperature of something, like food, as in "I'll heat up the leftovers for dinner." It can also be used metaphorically to describe situations becoming more intense or contentious, for example, "The debate started to heat up as more participants joined in." Although it is used more commonly in everyday communication, it can appear in formal contexts when discussing technical processes, such as heating in scientific or engineering settings. The phrase can be split or kept together without changing its meaning: both 'heat up the soup' and 'heat the soup up' are used interchangeably. This flexibility, along with its clear, descriptive function, makes 'heat up' a versatile verb in various contexts.
A2
Elementary
1. To make something warm or hot by applying heat.
I need to heat up some soup for dinner.
The oven will heat up in about ten minutes.
2. To become warm or hot, usually referring to an increase in temperature.
The room started to heat up when we closed all the windows.
The debate really heated up after the new data was presented.
3. To intensify or escalate, often referring to situations, emotions, or activities.
The competition is heating up as the final round approaches.