The phrase "vapor phase" refers to the gaseous state of a substance. It is when a substance transitions from a liquid or solid state to a gas or vapor state. Full definition
That equation does not distinguish between solid, melt and vapor phases of material — a limitation, Melosh asserts, because «vapor pressure seems to have been involved in a collision that spewed vaporized Earth material into orbit.» (scientificamerican.com)
Gallium is a metal with a low melting point; unlike graphene and many other 2 - D structures, it can not yet be grown with vapor phase deposition methods. (sciencedaily.com)
At any moment, the atmosphere contains an astounding 37.5 million billion gallons of water, in the invisible vapor phase. (drtimball.com)