boil off(redirected from boil something off)
1. To remove a liquid through evaporation as a result of boiling. A noun or pronoun can be used between "boil" and off." You'll need to boil the excess water off before the solution can be used.
2. To be removed (from something) through evaporation as a result of boiling. Even though there is cognac in it, the alcohol boils off when the dish is being cooked.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.