Hidden Thesaurus on iPhone in iOS 12: How to Unlock

iOS 12 includes a built-in thesaurus that works alongside the dictionary, but it’s not immediately obvious how to access it. This guide shows you how to reveal synonyms for any word you type on your iPhone, using only the built-in Look Up feature—no third-party apps needed.

What You’ll Need

• An iPhone running iOS 12 (or later, though steps are for iOS 12)
• Any app where you can select text, such as Notes, Safari, or Messages
• An active internet connection for the first lookup (dictionary data downloads once)

Step-by-Step

1. Open any app that displays text you can select, like Notes or Safari.
2. Tap and hold on a word until the magnifying glass appears, then release. The word gets highlighted with selection handles.
3. Drag the blue selection handles to adjust the selection if needed—make sure only the word you want synonyms for is selected.
4. In the pop-up menu that appears above the selection, tap Look Up. (If you don’t see it, tap the right arrow in the menu to reveal more options.)
5. A panel slides up from the bottom showing the dictionary definition. Scroll down past the definition and usage notes.
6. Look for the Synonyms section—it lists several related words with a brief label like “Synonyms” or “Thesaurus.”
7. Tap any synonym to see its own definition and synonyms, or tap Done to close the panel.
8. If you want to copy a synonym, tap and hold on it in the list, then choose Copy from the menu.

Common Mistakes

• Selecting more than one word: Look Up only shows synonyms for a single word. If you select a phrase, you’ll only get dictionary definitions, not thesaurus entries.
• Looking up a word that isn’t in the dictionary: Proper nouns, brand names, and very technical terms may have no synonyms listed.
• Expecting it in every app: Some third-party text fields may not support Look Up. Try in Apple’s own apps like Notes or Safari.
• Skipping the scroll: The synonyms section is below the definition. If you stop at the first line, you’ll miss it.

Tips

• You can also trigger Look Up by tapping the word with three fingers? No—just tap and hold as described; that’s the standard gesture.
• If you use this often, add the Look Up option to your shortcut bar by going to Settings > General > Dictionary and making sure “English” (or your language) is downloaded.
• For faster access, select the word and use the Share > Look Up option if available in the share sheet.
• The thesaurus works offline once the dictionary is downloaded, so you can use it on a plane or in airplane mode.

Troubleshooting

Look Up doesn’t appear in the menu: Make sure you have a dictionary downloaded. Go to Settings > General > Dictionary, tap “Manage,” and download at least one English dictionary. Then try again.

No synonyms shown: The word may not have a thesaurus entry. Try a more common word or check the spelling. If you’re looking up a plural or past tense, look up the base form instead.

The panel opens but is blank: This usually means the dictionary download failed. Go to Settings > General > Dictionary, delete the dictionary, and re-download it over Wi-Fi.

Synonym list is too short: iOS 12’s built-in thesaurus is basic. For more synonyms, you can use the Look Up result’s “Search Web” link to find an online thesaurus.

Frequently Asked Questions

Does this work on all iPhones with iOS 12? Yes, as long as the device supports iOS 12 (iPhone 5s and later).

Can I change the language of the thesaurus? Yes, the thesaurus follows the dictionary language you download in Settings > General > Dictionary. You can have multiple languages, but Look Up shows synonyms only for the primary language of the word.

Is there a way to see synonyms without opening Look Up? No, Look Up is the only built-in method. Third-party keyboard extensions like Gboard have their own thesaurus, but that’s separate.

Why does my iPhone show “No Synonyms Found”? That happens for words that aren’t in the dictionary’s thesaurus database, like very new slang or technical jargon.

Can I use this in any app? Look Up works in most apps that use standard iOS text selection, but some apps disable it. Apple’s own apps (Notes, Mail, Safari) are the most reliable.

Will this use data? Only the first time you look up a word, when the dictionary downloads. After that, it works offline.

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