Canary in the mine意思

"Canary in the mine" is an English idiom that comes from the historical practice of using canaries as warning signals for the presence of toxic gases in coal mines. Canaries are birds that are particularly sensitive to these gases, so if they became sick or died, it would indicate to the miners that they needed to evacuate immediately to avoid danger.

The phrase has come to mean a warning or indicator of a larger problem. It is often used metaphorically to refer to something or someone that serves as an early warning signal of potential danger or trouble. For example, if an employee notices a decline in sales and brings it to the attention of management, they might be described as "the canary in the mine" for alerting the company to a potential financial issue.