A device that makes a clicking sound when pressed, often used as a remote control or training tool for animals and people.
From click (an imitative word for the sound) + -er (device that does something). The word became common in the 20th century with remote controls and training devices.
Dog trainers use clickers because the sharp 'click' sound marks the exact moment a dog does something right, and that precise timing is way more effective than saying 'good dog!' a second later!
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