If you are experiencing this issue as I did — the Dictionary/definition keeps popping up when you type or use the mouse, here’s the solution for you.
The problem appeared on my MacBook from yesterday, which I had no idea what I did. I was just typing on Google docs and some words got automatically highlighted, followed by a Dictionary app showed up that provided a definition of the word the mouse pointed at (see this screenshot). The weirdest thing was that my screen sometimes enlarged itself.
At first, I thought it was due to that I haven’t updated system to latest OS — so I went ahead and upgraded OS. But the issue still persisted.
The real solution
It’s actually quite simple. All you need to do is disable an option via in the trackpad setting.
Step 1: on your Mac, open System Preferences.
Step 2: click Trackpad.
Step 3: under Point & Click tab, uncheck “Look up & data detectors”.
That’s it. Quite simple, right?
Not sure how I messed up and checked this option. My guess is that I might have mis-clicked it while I was cleaning my Mac screen and keyboard.
Anyway, hope this tip has helped you out.