adjective / noun

observable

uhb-ZUR-vuh-buhl/əbˈzɜːrvəbl/

Able to be seen, noticed, or measured.

The tile's crack is observable and wide enough to measure with a ruler.

A plainly visible crack in a white ceramic tile is both noticed and measured: a woman points at the dark gap while holding a small ruler across it.

Etymology

obLatinbefore, in front of

+servLatinto watch, keep safe

+ableLatincapable of being

The compound built on “watch, keep safe” also meant “note” or “heed.” Observable shifted from something deserving attention to something capable of being perceived, the basis of its present sense.

In context

CEFISES at UCLouvain38:08

we have to be able to observe a difference and the way to reconcile the invariance of the Symmetry transformation with an observable difference

Valeriya Chasova, "Observable Diffeomorphisms (or, How to Limit the Hole Argument and Extend DES)"

More examples

There is no observable difference between the two samples.
Some changes are observable only with sensitive instruments.
The researchers track two observables: temperature and pressure.

Forms

observable · observables

observe verb — To notice or examine something carefully.

observability noun — The quality of being detectable or measurable.

Similar words

detectable: Emphasizes that something's presence can be discovered.
visible: Specifically means able to be seen, rather than otherwise detected.
measurable: Emphasizes that an amount or degree can be determined.