- The process by which molecules of a liquid turn into a gas, the vapour, below the liquid’s boiling point, when they acquire enough energy to leave the body of the liquid. The term is also used by analogy to describe the process by which matter and energy can leak out of a black hole, leaving nothing behind. In the case of small black holes this process can be so rapid that they explode, because their temperature rises rapidly as more material is removed.
- Loss, from a liquid, of moisture in vapor form.
- loss of moisture from wine into the atmosphere, necessitating the regular topping up of barrels while the wine is maturing unless the wine is on ullage for a purpose, e.g. in sherry-making