Definition of "alarm bell" [alarm bell]

• Used other than as an idiom: see alarm,‎ bell. (noun)
• A sudden awareness of danger. (noun)

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• "A quiet alarm bell went off in the back of Ferrol's brain."
• "He was attempting then to get the Mooncat’s nose turned away from the distant volcano ranges towards which she seemed determined to point when the detector needles slapped flat against their pins and the alarm bell sounded."
• "Tom Swift cried as an alarm bell broke the midnight stillness of his rocket laboratory on Fearing Island."