volatile

Evaporating or vaporizing readily under normal conditions.

Of a substance, explosive.

Of a price, variable or erratic.

Its pricing is highly volatile — and therefore highly risky. For all its nosebleed ascents, bitcoin also has had some gut-punching plunges. Between November 2021 and November 2022, for example, the price of bitcoin dropped 75%, from $64,455 to $16,196, according to data on coinmarketcap.com.

Of a person, quick to become angry or violent.

a volatile man

Fickle.

A chemical or compound that changes into a gas easily.

A variable that is volatile, i.e. has its associated memory immediately updated with any change in value.

Operations on C++ volatiles do put the compiler on notice that the object may be modified asynchronously, and hence are generally safer to use than ordinary variable accesses.