The input of words into a text string in a communication terminal is handled by recording a key stroke sequence inputted for characterising one of said words, and comparing said key strokes sequence with candidates in a word completion directory in order to find word completion candidates matching said key stroke sequence. One of said matching word completion candidates is displayed in the display for selection by the user. When the user selects a word which exceeds a first predetermined number of characters the selected word is added to the directory including a plurality of word completion candidates, if the selected word is not present there already.