3. The searching method according to claim 2 , wherein, the document includes a headword and an explanatory text which explains the headword; and, the preference determination step determines the output preference of the document based on a difference between a length of the headword and a length of the search string.
3. The searching method according to claim 2 , wherein, the document includes a headword and an explanatory text which explains the headword; and, the preference determination step determines the output preference of the document based on a difference between a length of the headword and a length of the search string. 4. The searching method according to claim 3 , wherein, the preference determination step determines the output preference, for each of the extracted documents having same difference between the length of the headword and the length of the search string, further based on a distance between a first character of the headword and the search string in an ascending order.