From Longman Dictionary of Contemporary EnglishI shudder to thinkI shudder to thinkspokenBAD used to say that you do not want to think about something because it is too unpleasantI shudder to think what they’ll say when they see the mess the house is in. →shudder
Examples from the Corpus
I shudder to think• I never know how carefully. I shudder to think.• Palestrina! I shudder to think what I should do when her next socialinvitationarrives in the letterbox!• I regularly see them sent out alone on shopping errands. I shudder to think what might happen on their way home.• I shudder to think what will happen to him now.