How to Add Personal Dictionary on Nexus 4 and what is it for? Well, it helps the phone to identify some of your own words which can not be found in any other dictionary. To customize your personal dictionary and add words in the user dictionary, do as follows:
1. Open "Setting" and go to "Language & Input"
2. Tap "Personal Dictionary"
3. Tap the "Add" button on the top right to add your words
4. Add Phrase, shortcut, and the language (you can select a specific language or apply the words to all languages).