unsufferable

• insufferable

un- +‎ suffer +‎ -able

• IPA^(key): /ʌnˈsʌfəɹəbəl/

unsufferable (comparative more unsufferable, superlative most unsufferable)

1. Not able to be suffered, difficult or impossible to endure; insufferable.
   • John Evelyn; The diary of John Evelyn, Frederick Warne and Co., page 129

     The heate of this place is wonderfull; the earth itselfe being almost unsufferable, and which the subterranean fires have made so hollow, by having wasted the matter for so many years, that it sounds like a drum to those who walke upon it...

   • 1813; Isaac Watts; The works of the Rev. Isaac Watts D.D. in nine volumes, Volume 6, Edward Baines, page 504

     It is possible that these expressions of God's covering Moses with his hand while the glory of God past by, and Moses seeing the back parts of God, may signify no more than this, that in this particular appearance of God he arrayed himself in beams of light of such unsufferable splendor, that it would have destroyed the body of Moses had not God sheltered and protected him...

   • 1839; Edward Wells, William Dowsing; The rich man's duty to contribute liberally to the building, rebuilding, repairing, beautifying, and adorning of churches, Oxford: T. Combe, page 139

     ...would it not be an unsufferable crime in a steward, on the strength of the forementioned false imagination, for to lay out great sums of his lord's money on building himself a noble house, and the mean while to let his lord's house lie in a mean, or even ruinous condition?

Like insufferable, this is usually meant as a derogatory expression of frustration targeted at something.