¹ bolt noun

• a bright line of light that appears in the sky during a storm : a flash of lightning —often used figuratively in the phrases a bolt from the blue and a bolt out of the blue
• a sliding bar that is used to lock a door or window
• the part of a lock that is moved by a key

² bolt verb

• to move or go very suddenly and quickly from or to a particular place, position, or condition
• to run away suddenly and quickly
• to suddenly leave a political party, team, etc.

³ bolt adverb

• with the back in a very straight position