Definition from Wiktionary, the free dictionary
- Present participle of boil.
- The process of changing the state of a substance from liquid to gas by heating it to its boiling point.
process of changing the state of a substance
- That boils or boil.
- boiling kettle
- boiling oil
- (of a thing, informal, hyperbolic) Extremely hot.
- The radiator is boiling – I'm going to turn it down a bit.
- (of a person, informal, hyperbolic) Feeling uncomfortably hot.
- I'm boiling – can't we open a window?
- (of the weather, hyperbolic) Very hot.
- It's boiling out today!
- For usage examples of this term, see the citations page.
Derived terms 
of a thing: extremely hot
of a person: feeling uncomfortably hot
of the weather: very hot
boiling (not comparable)
- (of adjectives associated with heat) Extremely
- He was boiling mad.