heat vs hot up

heat

verb
  • To become hotter. 

  • To excite ardour in; to rouse to action; to excite to excess; to inflame, as the passions. 

  • To arouse, to excite (sexually). 

  • To excite or make hot by action or emotion; to make feverish. 

  • To cause an increase in temperature of (an object or space); to cause to become hot (often with "up"). 

noun
  • A condition where a mammal is aroused sexually or where it is especially fertile and therefore eager to mate; oestrus. 

  • A hot spell. 

  • The output of a heating system. 

  • An attribute of a spice that causes a burning sensation in the mouth. 

  • One cycle of bringing metal to maximum temperature and working it until it is too cool to work further. 

  • The condition or quality of being hot. 

  • Heating system; a system that raises the temperature of a room or building. 

  • A period of intensity, particularly of emotion. 

  • A fastball. 

  • An undesirable amount of attention. 

  • A preliminary race, used to determine the participants in a final race 

  • A violent action unintermitted; a single effort. 

  • A stage in a competition, not necessarily a sporting one; a round. 

  • In omegaverse fiction, a cyclical period in which omegas experience an intense, sometimes irresistible biological urge to mate. 

  • One or more firearms. 

  • Thermal energy. 

  • The police. 

hot up

verb
  • To become more heated. 

  • To make or become more sexually appealing, enticing or exciting. 

  • To increase in temperature. 

How often have the words heat and hot up occurred in a corpus of books? (source: Google Ngram Viewer )