How to Look Up a Word Instantly on Mac (Dictionary)

Every word on your Mac's screen is one gesture away from its definition. Force click it, tap it with three fingers, or hover and hit Ctrl+Cmd+D — a popover appears with the dictionary entry, thesaurus, and a Wikipedia summary, without leaving the app you're in. Here's every lookup method, and how to make the results richer.

The three fastest lookups

• Force click — on a Force Touch trackpad (every MacBook since 2015 and the Magic Trackpad 2 onward), press firmly on a word until you feel the deeper click. The definition popover opens right at the word.
• Three-finger tap — if you'd rather not press hard, change the gesture: System Settings → Trackpad → Point & Click → Look up & data detectors → Tap with Three Fingers. A light triple-finger tap on any word now does the same thing.
• Ctrl+Cmd+D — the keyboard route, and the only one that works with a mouse. Hover the pointer over the word (no need to select it) and press the combo. In most apps you can even hold the keys down and slide the pointer across text to look up word after word.

There's also the menu route — select a word, right-click, choose Look Up — and Spotlight: press Cmd+Space, type the word, and a Definition result appears in the list. Five ways to the same popover; the one you'll keep is whichever matches how your hands already move — trackpad people force click, keyboard people learn Ctrl+Cmd+D once and never stop.

What the popover shows

The lookup panel isn't just a dictionary. Depending on the word, you'll get the New Oxford American Dictionary entry, thesaurus synonyms, a Siri Knowledge or Wikipedia card, and app-specific results like Music or Movies for names. Click any section to open the full entry in the Dictionary app.

Make Dictionary smarter

1. Open the Dictionary app itself (Cmd+Space, type "Dictionary").
2. Choose Dictionary → Settings.
3. Tick the sources you want: the American English thesaurus, the Apple Dictionary (Apple's own tech terms), Wikipedia, and full dictionaries for other languages — Spanish, French, German, Japanese, and many more, including bilingual ones like Spanish–English.
4. Drag sources into the order you want them to appear.

Everything you enable here also shows up in the lookup popover and in Spotlight definitions, so thirty seconds of setup upgrades every lookup you'll ever do. The language dictionaries download on first use and then work offline.

The Dictionary app is better than it looks

Beyond feeding the popover, the app itself rewards a visit. The search field matches as you type, so it doubles as a spelling checker — type the first few letters and scan the candidates. With bilingual dictionaries enabled, it becomes a fast translation lookup for single words: search in either language and both directions appear. Tabs across the top let you jump between sources for the same word, and File → New Window (Cmd+N) lets you keep a thesaurus window open beside your writing app all day. Front matter hides in there too — usage guides and grammar notes ship with the Oxford dictionaries, free with your Mac.

If lookup stops working

Two usual suspects. First, the trackpad gesture may be off — check System Settings → Trackpad → Point & Click → Look up & data detectors isn't set to Off. Second, some apps (a few Electron-based editors, virtual machines) don't expose their text to macOS, so the popover has nothing to read; the Ctrl+Cmd+D trick fails there too. Copy the word into any native app, or use Spotlight, and you're back in business.