Observable

Full definition of observable

Adjective

1. Able to be observed.
• The strange new star was at the edge of the observable universe
2. Deserving to be observed.
• Easter is an observable holiday

Noun

1. (physics) Any physical property that can be observed and measured directly and not derived from other propertiesTemperature is an observable but entropy is derived.In quantum mechanics, observables correspond to Hermitian operators. Also, they act a lot like random variables. Taking their average one may recover something resembling a classical observable.