alarm bell
A sudden warning or intimation of danger, risk, or ill fortune. (Often pluralized.) Alarm bells were going off in my head when I saw the panicked expression on her face.
cause for alarm
A reason to be worried, frightened, or concerned about something. The X-ray showed a slight discoloration in my lungs, but my doctor assured me it was no cause for alarm. There was cause for alarm when we noticed our boss shredding all the files in her office.
sound the alarm
1. Literally, to activate an alarm. I think I see smoke coming from the warehouse. Someone run upstairs and sound the alarm!
2. To alert other people about something dangerous, risky, or troublesome. A number of top economic advisors tried to sound the alarm before the economic crash, but no policy makers seemed to heed their warnings.
raise the alarm
1. Literally, to activate an alarm. I think I see smoke coming from the warehouse. Someone run upstairs and raise the alarm!
2. To alert other people about something dangerous, risky, or troublesome. A number of top economic advisors tried to raise the alarm before the economic crash, but no policy makers seemed to heed their warnings.
false alarm
A benign situation initially mistaken for an emergency. Mary thought she was going into labor, but it turned out to be a false alarm. When the smoke detectors started beeping, we thought the building was on fire, but it was just a false alarm caused by faulty wiring.