- Variable (programming): An identifier (usually a letter, word, or phrase) that is used to identify a value stored in the system's memory.
- Variable bush viper: Venomous viper species found in west and central Africa.
- Variable star: A star whose apparent brightness exhibits periodic variations
- : Pulsating variable star which exhibits a relation between period of variation and absolute luminosity as a result of which they are good indicators of cosmic distances.
- Random variable: a variable whose value is determined by chance rather than as a result of a known cause.