- beyond the ability to understand or imagine; inconceivable
- so extreme, foul, etc. as to be unfit to be imagined or considered: unthinkable war crimes
Origin of unthinkableMiddle English unthenkable
- Impossible to imagine; inconceivable: “The inert gases have been coaxed into combination, and I have seen a fluoride of xenon, unthinkable in the 1940s” (Oliver Sacks).
- Not worth considering because of being socially unacceptable, too difficult, or too risky: Raising taxes was politically unthinkable.
- Abhorrent; monstrous: unthinkable brutality.
- un·think′a·bil′i·ty, un·think′a·ble·ness
- Incapable of being believed; incredible.
- Inconceivable or unimaginable; extremely improbable in a way that goes against common sense.
- Nothing is unthinkable, nothing impossible to the balanced person, provided it comes out of the needs of life and is dedicated to life's further development - Lewis Mumford
un- +"Ž thinkable