unsupportable, unsufferable, insufferable, unendurable, impossible, unbearable, unacceptable, bitter, untolerable, insupportable, more...

bearable, tolerable, endurable

intolerable pain, intolerable heat, intolerable noise, intolerable smell, intolerable cruelty, more...

be unendurable,   can't take it,   unable to bear,   too extreme to bear,   not tolerable,   unable to endure,   can't stand at all,   unable to bare,   was so unbearable,   cannot take it