The Dictionary (or “Look Up”) feature in iOS allows users to highlight any text within an application (such as Safari, Mail, or Notes) and select “Look Up” to view dictionary definitions, Wikipedia summaries, and other contextually relevant information. While this is an excellent educational and reference tool, it operates by maintaining a database of offline dictionary files locally on the device. In highly locked-down environments, or on older devices struggling with storage constraints, administrators or users may wish to completely remove these dictionary files to free up space, simplify the text-selection context menu, or prevent users from accessing built-in reference materials during secure testing/exam scenarios.
This guide explains how to completely disable the Dictionary “Look Up” feature system-wide on an iPhone by purging the local dictionary databases.
Disable Dictionary Lookups
iOS does not have a master “off” switch for the Look Up feature. However, the feature relies entirely on downloaded dictionary packs. By unchecking and deleting all downloaded packs, the feature becomes functionally inert.
- Unlock your iPhone and open the main Settings app.
- Scroll down and tap on General.
- Scroll down and tap on Dictionary.
- You will see a list of available dictionaries (e.g., Apple Dictionary, New Oxford American Dictionary, etc.). Any dictionary with a checkmark next to it is currently downloaded and active on your device.
- Methodically tap on every single dictionary that has a checkmark to uncheck it.
- Once you uncheck a dictionary, iOS immediately deletes the local database file associated with it. Ensure that zero items on this list have a checkmark.
Verify the Configuration Lockdown
By removing all dictionary files, the local querying engine has no data to reference when a user attempts a lookup.
To verify the lockdown is active, open the Notes app or Safari and type or locate a common word (e.g., “Computer”). Double-tap the word to highlight it and bring up the iOS text-selection context menu. Tap the Look Up option. Instead of displaying a definition or a rich-text card, the resulting panel will state “No Content Found” or offer to search the web instead (if web search is allowed). The native on-device dictionary definitions are now completely disabled and removed from the system.