A word completion system that can automatically predict unrestricted word completions for data entries in an unstructured portion of a data file. The word completion system applies prediction criteria to avoid annoying the user by displaying an excessive number of wrong suggestions. Suggested word completions, which may change as the user types a partial data entry, are displayed in a non-disruptive manner and selected using traditional acceptance keystrokes, such as the "tab" key or the "enter" key. The word completion system may be deployed on an individual application program basis or on a application-independent basis. Because different word suggestion lists may be appropriate for different application programs, and for different data files created with the same application program, the word completion system allows the user to select one or more suggestion lists for use with each data file. A user interface allows the user to customize each suggestion list on an on-going basis. Each suggestion list may contain dynamic word completions that are tied to dynamic parameters maintained by the computer system, such as the time, date, registered user, and so forth. Each suggestion list may also be tied to contextual information, such as structured data fields or context labels assigned manually or by a document-creation aid known as a "wizard."