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?
Cite this Entry
“Heat up.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/heat%20up. Accessed 16 Aug. 2026.
Copy CitationLove words? Need even more definitions?
Merriam-Webster unabridged
