The Accidental Definitions
macOS trackpads are incredibly feature-rich, supporting a wide array of multi-touch gestures. One such feature is the “Look Up” shortcut. By default, if you perform a three-finger tap (or a Force Click on newer trackpads) on any selectable text within Safari, Mail, Pages, or most native macOS applications, the operating system will automatically launch a small pop-up window displaying the dictionary definition, thesaurus entry, or Wikipedia summary for that specific word. While incredibly useful for writers and students, this feature is highly prone to accidental activation. If you rest your fingers heavily on the trackpad while scrolling or reading, you will frequently trigger this dictionary pop-up, interrupting your workflow and obscuring the screen.
Disabling the “Look Up” Gesture
To stop macOS from automatically launching the dictionary pop-up every time you tap the trackpad slightly too hard, you must disable or change the specific gesture mapped to the “Look Up & data detectors” feature.
Click the Apple logo in the top-left corner of the menu bar and select System Settings. In the left-hand sidebar, scroll down and click on Trackpad (if you are using a Magic Mouse, click Mouse). In the main Trackpad window, select the Point & Click tab at the top. Look for the option labeled Look up & data detectors. Next to it is a drop-down menu that is likely set to “Force Click with one finger” or “Tap with three fingers”. Click this drop-down menu and select Off. The change takes effect immediately. You can now tap, click, and rest your fingers on your trackpad without the macOS dictionary automatically launching mid-sentence.