If something is untenable, you can't defend it or justify it. If your disagreement with your teacher puts you in an untenable position, you better just admit you made a mistake and get on with it.

When untenable entered English in the 17th century it meant "unable to be held against attack." That sense still holds true: you can use the adjective untenable to describe any situation, position, or theory that simply can't be defended. Untenable is a great word to use when you want to criticize something, whether it's a flawed system or a referee's bad call.

Definitions of untenable

adj (of theories etc) incapable of being defended or justified

not reasonable; not showing good judgment

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