Predictive text input - definition
Allows the user to enter text by pressing only one key per letter on a keypad where multiple letters share keys. As a word is entered, the phone automatically compares all possible letter combinations against a built-in dictionary of words, and determines which word was intended to be typed by the user.
It is possible to scroll (without re-typing) through all possible matches until the right word is found. This feature allows faster and easier typing than the standard typing method where some keys must be pressed several times until the right letter is displayed on the screen (a.k.a. multi-tap).
The most popular types of predicative text entry are T9 and Motorola's iTAP.