volatile
In general, volatile (from the Latin "volatilis" meaning "to fly")is an adjective used to describe something unstable or changeable.
In computers, volatile is used to describe memory content that is lost when the power is interrupted or switched off. Your computer's ordinary memory (or RAM ) is volatile memory.
Volatile memory contrasts with nonvolatile memory , memory that does not lose content when power is lost, that has a continuous source of power, or does not need to have its memory content periodically refreshed.