A reduced keyboard disambiguating system. The keyboard has twelve to sixteen keys, nine of them labeled with numerous letters and other symbols, and those nine plus one more are associated each with one of the ten digits. Textual entry keystrokes are ambiguous. The user strikes a delimiting “Select” key, or a key with an unambiguous character interpretation, at the end of each word, delimiting a keystroke sequence that could match any of a plurality of words associated with the same keystroke sequence. Each input keystroke sequence is processed with a complete vocabulary, and words which match the sequence of keystrokes are presented to the user in order of decreasing frequency of use. The vocabulary is stored in a special format that supports significant data compression without requiring additional processing. In addition, stems of longer words whose initial letters match the sequence of keystrokes are also presented to the user in order of decreasing frequency of use. If the frequency of the words associated with a stem is high enough, that stem is displayed as the default word object. Activations of an ambiguous key associated with a plurality of punctuation characters are disambiguated from the context of the surrounding keystrokes.