insufferable.

From Late Middle English insufferable (“unbearably painful, intolerable”), and then either: * from in- (prefix meaning ‘not’) + sufferable, souffrable (“bearable, endurable, tolerable; allowable, permissible; able to or willing to bear hardship; forbearing, long-suffering; calm, self-restrained, slow to anger; capable of suffering”) (from Anglo-Norman sufferable, souffrable, and Old French souffrable, suffrable (“sufferable, tolerable”)); or * from Old French insouffrable (“which cannot be endured or suffered; something insufferable or unendurable”) (now dialectal), from in- (prefix meaning ‘not’) + souffrable, suffrable. From Old French souffrable, suffrable are derived from Medieval Latin sufferābilis, from Latin sufferre + -ābilis (suffix meaning ‘able or worthy to be’); while sufferre is the present active infinitive of sufferō, subferō (“to bear or carry under; to bear, endure, suffer, undergo”), from sub- (prefix meaning ‘below, under’) + ferō (“to bear, carry; to endure, suffer, tolerate”) (ultimately from Proto-Indo-European *bʰer- (“to bear, carry”)). The English word is analysable as in- (prefix meaning ‘not’) + sufferable.