2. The word input method according to claim 1 , wherein the predetermined number of letters is 6.
1. A word input method, including the steps of: having a word storage unit wherein words having less letters than a predetermined number and words having more letters than the predetermined number are divided; selectively and sequentially inputting one or more letters containing the first letter of the word to be inputted; extracting a first word from the word storage unit of words having less letters than a predetermined number, wherein the first word coincides with the input one or more letters in a sequence from the first letter; extracting a second word from the word storage unit of words having less letters than the predetermined number, wherein the second word corresponds with the input one or more letters at least partially comprising the first letter; extracting a third word from the word storage unit of words having more letters than the predetermined number, wherein the third word coincides with the input one or more letters in a sequence from the first letter; extracting a fourth word from the word storage unit of words having more letters than the predetermined number, wherein the fourth word corresponds with the input one or more letters at least partially comprising the first letter; dividing the first, second, third, and fourth words into a first group having less letters than the predetermined number and a second group having more letters than the predetermined number; calculating a frequency for each of the first, second, third, and fourth words; displaying, on a word display window, the first and second groups, wherein the words in each of the first and second groups are in the order of the frequency; receiving a selection of a word from among the words displayed on the display window; and enabling the letters to be converted and completed into a selected word during inputting when the word is selected by a user from among the words displayed on the word display window.