Modern electronic devices accept text inputs for many different purposes, such as for composing emails, text messages, documents, and the like. In the case of small, handheld electronic devices, inputting text can be cumbersome, slow, and prone to errors. In particular, the small keyboards used by these devices (including both mechanical and touchscreen-based keyboards) make entering all but the shortest words difficult, and tend to increase spelling, grammar, and punctuation errors. In some cases, electronic devices provide word suggestion functions (e.g., spell-check and/or word-completion functions) to help increase input speed and decrease input errors. These devices typically rely on locally stored dictionaries in order to identify errors and suggest corrections, and/or to suggest complete words based on partially entered text strings. For example, a mobile phone may consult a locally stored dictionary (e.g., a list of words) to determine that the word “teh” is misspelled because it does not appear in the dictionary. The mobile phone may also provide suggestions of words that are in the dictionary that may be suitable replacements for the misspelled word (e.g., “the”). In another example, the mobile phone receives a partial text string (e.g., “dict”) and presents candidate complete words for that partial text string (e.g., “dictionary” and “diction”).
Handheld devices, however, have limited memory and processing capacity, and it is not practical to store every possible word in a given language on these types of devices just to provide spell-check or word-completion functions. Moreover, many words relate to specialized subjects, and are only used by a subset of the general population. For example, legal words and/or phrases (e.g., “ex parte,” “affidavit,” “appurtenant,” etc.) are less likely to be used by non-lawyers, and names of professional athletes are less likely to be used by non-sports fans. Thus, while a comprehensive dictionary that includes all of these types of words will provide robust spell-check and word suggestion functionalities to all users, it requires more storage space and results in longer processing times. At the same time, the absence of these words can be an inconvenience for users who use them frequently.