iPhone and iPad Dictionaries: How to Choose & Look Up Words

To look up a word on an iPhone or iPad, simply tap and hold the word in any text, then choose “Look Up� from the pop-up menu. To choose a dictionary, go to Settings > General > Dictionary, then select which languages and specialty dictionaries you want to download and use.

How the Built-in Look Up Feature Works

Apple includes a system-wide dictionary that works across almost every app—Safari, Mail, Notes, Messages, and even third-party apps that use the standard text-selection menu. When you long-press a word, a magnifying glass appears; release, and a bar offers options like Copy, Define, and Speak. Tapping “Look Up� opens a panel with the definition, part of speech, and often a thesaurus entry or Wikipedia snippet.

The feature relies on downloaded dictionary files. Your iPhone or iPad ships with a basic English dictionary pre-loaded, but you can add more. Each dictionary is a separate download, usually a few megabytes, and once installed it works offline—no internet connection needed for definitions.

How to Choose Which Dictionaries to Install

Choosing the right dictionaries depends on what you read and write. Here’s what to consider:

Your primary language – If you read in English, the New Oxford American Dictionary (for US English) or Oxford Dictionary of English (for UK English) is the default. Both are excellent.
Second languages – If you study French, Spanish, German, Chinese, Japanese, or other languages, install the bilingual dictionary for that language. You can have multiple installed at once.
Specialized needs – Apple offers a thesaurus, an Apple Dictionary (for tech terms), and a Wikipedia lookup. If you’re a student, the thesaurus is very useful. If you read historical texts, consider the “Shakespeare� dictionary or “Dictionary of Old English.�
Offline use – All downloaded dictionaries work offline. If you travel or have limited data, download them before you need them.

To manage them: open Settings > General > Dictionary. You’ll see a list of available dictionaries with download icons. Tap to download. Once downloaded, they appear with a checkmark. You can reorder them by tapping “Edit� and dragging, which affects which definition shows first when multiple dictionaries match.

How to Look Up a Word: Step-by-Step

Open any app with selectable text—Safari, Notes, Mail, or a book in Apple Books.
Tap and hold on the word until the magnifying glass appears, then release.
In the pop-up menu, tap “Look Up� (or the dictionary icon).
Read the definition in the panel that slides up. Swipe left/right to see other dictionaries if multiple are installed.
Tap outside the panel to close it.

If “Look Up� doesn’t appear, the word might be in a PDF or image. For PDFs, try selecting the text first; if it’s an image, you’ll need to use the Live Text feature (iOS 15 and later) by tapping the scan icon in the corner of the photo.

Common Problems and Fixes

Sometimes the Look Up feature doesn’t work as expected. Here are the most common issues and solutions:

No definition appears – Check that you have at least one dictionary downloaded in Settings > General > Dictionary. If none are checked, the feature has nothing to show.
Definition is in the wrong language – Reorder your dictionaries in Settings > General > Dictionary so your primary language is first. Tap “Edit� and drag.
Look Up is grayed out – This happens when the text is not selectable, such as in some PDF viewers or image-based content. Try a different app or use Live Text.
Dictionary download fails – Ensure you have a stable internet connection and enough storage. Go to Settings > General > iPhone Storage to check free space.
Word is not in the dictionary – Proper nouns, slang, and technical terms may not be included. The Wikipedia dictionary can help with names and places.

Built-in vs. Third-Party Dictionary Apps

The built-in Look Up is fast and convenient, but it has limits. It doesn’t offer example sentences for every word, and its coverage of slang or niche jargon is thin. If you need more depth, consider a dedicated dictionary app. Popular options include:

Merriam-Webster – Free with ads, excellent for US English, includes audio pronunciations and word of the day.
Oxford Dictionary of English – Paid, but very thorough with example sentences and usage notes.
WordReference – Free, best for bilingual dictionaries and forum discussions on usage.
Etymology Online – Free, if you care about word origins.

The key difference: built-in Look Up works across all apps without switching, while third-party apps offer richer content but require you to copy/paste or open separately. For most users, the built-in is enough; for students or writers, a third-party app may be worth it.

Cost and Storage Considerations

All Apple-built dictionaries are free to download. They take up a small amount of storage—typically 1–5 MB each. The Wikipedia dictionary is larger, around 50 MB, because it contains a huge amount of data. Third-party apps vary: many are free with ads, while premium versions cost a few dollars. There are no subscription fees for Apple’s dictionaries.

If you’re low on storage, you can delete dictionaries you don’t use. Go to Settings > General > Dictionary, tap “Edit,� then tap the red minus sign. The dictionary is removed but can be re-downloaded anytime.

Alternatives to Look Up

If the built-in feature doesn’t meet your needs, here are other ways to look up words on an iPhone or iPad:

Ask Siri – Say “Hey Siri, define [word].� Siri will show a definition from the built-in dictionary.
Spotlight Search – Swipe down from the middle of the Home Screen, type the word, and scroll to the “Dictionary� section.
Shortcuts – Create a shortcut that opens a dictionary app with the selected word. This is more advanced but can save time.
Live Text – In a photo, tap the Live Text icon, select the word, and choose “Look Up.�
Copy and paste into a search engine – Type “define [word]� in Safari or Google for a quick definition, though this requires internet.

Frequently Asked Questions

Why does Look Up not work in some apps?

Look Up only works when the app uses the standard text-selection system. Some apps, like certain PDF readers or games, disable text selection. If you can’t select the text, Look Up won’t appear. Try taking a screenshot and using Live Text, or copy the text if possible.

Can I add my own custom dictionary?

No, Apple does not allow adding custom dictionary files to the system Look Up. You can use third-party apps that let you build custom word lists, but they won’t integrate with the system-wide Look Up.

Does Look Up work offline?

Yes, once a dictionary is downloaded, it works fully offline. The Wikipedia dictionary also works offline, but it’s a snapshot, not live. If you need up-to-date information, you’ll need an internet connection.

How do I change the default dictionary language?

Go to Settings > General > Dictionary, tap “Edit,� then drag your preferred dictionary to the top of the list. The first dictionary in the list is the one that shows first when you look up a word.

Can I look up words in a foreign language without changing my system language?

Yes. Install the bilingual dictionary for that language in Settings > General > Dictionary. Then, when you look up a word in that language, the definition will appear in your system language. You can also look up English words and see translations in the foreign dictionary.

Is there a way to see the pronunciation of a word?

Yes, most Apple dictionaries include phonetic spelling and an audio pronunciation button. Tap the speaker icon next to the word to hear it. If you don’t see it, make sure you have the latest dictionary version.

General steps for current mainstream versions; menus can differ by device and version. See the disclaimer or report an error.

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