1. A server device comprising: a control unit collecting texts stored in a storage unit in response to an instruction from the outside or when a predetermined time is reached, extracting words from said collected texts, determining, as a general word, a word which appears at a frequency higher than a first predefined value for a first predetermined period, and which appears at a frequency varying within a second predefined value range for every second predetermined period shorter than said first predetermined period, and creating a general word list which enumerates said general words.