From Longman Dictionary of Contemporary Englishsit/stand bolt uprightsit/stand bolt uprightSITSTANDto sit or stand with your back very straight, often because something has frightened you She sat bolt upright in the back seat. → bolt
Examples from the Corpus
sit/stand bolt upright• She sat bolt upright, aches and pains quite forgotten.• He sat bolt upright and kept his eyes on the table in front of him.• Suddenly I sit bolt upright, feeling a familiar stab of panic that can mean only one thing: the videos!• She sat bolt upright; her features were strong, her manna forthright, even aggressive.• I walked across her line of vision and she sat bolt upright in annoyance.• We found her sitting bolt upright in bed with all the lights on.• She sat bolt upright in the back seat during the hour long journey, some of which was on a motorway.• Hotspur sat bolt upright in the saddle, his eyes narrowed on the hurtling horsemen, and never moved a hand.• Suddenly, Urquhart stood bolt upright, not twenty yards in front of the deer which froze in confusion. 