Your phone comes with a list of words that it references for predictive text
suggestions. Sometimes you may need to add a word to the predictive text dictionary, for
example a name or a specialized technical word.
While entering text using the QWERTY keyboard layout, if you tap any word on the
suggestion list, it is automatically added to the predictive text dictionary if it
was not in the dictionary already.
You can also add a word to the list manually:
On the onscreen keyboard, tap .
Tap User Dictionary.
Tap Add new.
Enter the word to add, and then tap OK.