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1. To start a fire or detonate an explosive device. He touched off the firework just as the school assembly was about to begin. Don't smoke in here! You might touch off the dry hay.
2. By extension, to trigger or initiate a reaction. A noun or pronoun can be used between "touch" and "off." Our teacher is so high-strung that the slightest provocation touches him off. The announcement touched off a riot in downtown Los Angeles.
touch someone or something off
Fig. to ignite or excite someone or something; to excite anger or chaos. She is very excitable. The slightest thing will touch her off. The appearance of the fox touched off a furor in the henhouse.
1. Cause to explode or fire; also, initiate, trigger. For example, The boys touched off a whole line of firecrackers, or These disclosures will touch off a public uproar. This idiom comes from early firearms, which were set off by putting a light to the touch-hole. Its figurative use dates from the late 1800s.
2. Depict very precisely, as in He touched off Teddy Roosevelt as well as it's ever been done. [Mid-1700s]
1. To cause something to explode or rapidly ignite: The spark touched off the puddle of fuel. A cigarette from a passing motorist touched the dry grass off and started a forest fire.
2. To trigger something; initiate something: Investigators wondered what could have touched the fire off. The news of the scandal touched off a public uproar.