observable

Possible to see or notice.

• There was no observable change.
• The treatment produced several observable effects.
• Some differences are observable only under bright light.

Similar words: noticeable, visible, detectable

Opposites: unobservable, imperceptible

Common phrases: observable change, observable effect, directly observable, observable universe

A physical feature, such as temperature, that can be directly measured.

• Temperature is an observable.
• The experiment measured several observables.
• Each observable has a value that can be recorded.

Common phrases: physical observable, measurable observable, quantum observable