unobservable

/ˌʌnəbˈzɜrvəbəl/
adjective
  1. Not able to be seen, noticed, or detected.
    • Some particles are unobservable even with powerful microscopes.
    • The effect of the drug on mood was subtle and nearly unobservable.
    • Dark matter is unobservable directly, but scientists infer its existence from gravity.
What does "unobservable" mean? | whatsthatwordmean | whatsthatwordmean