Recently, not only the person and things, but also words are imported by internationalization and informationization, and the scene using the loanword is increasing. However, these expressions are hard to understand for an child and the elderly person. Therefore, when such an expression is used for sentences, it might be hindered to understand entire sentences. Moreover, because an original word is omitted, it is likely to become the same expression as other words. Therefore, the alphabet abbreviation often has the polysemy. In this paper, a method of extracts an alphabet abbreviation from a sentence and judges the meaning of the expression is proposed. This method selects a correct meaning from two or more meanings of the alphabet abbreviation that suit for sentences, judging by using Wikipedia. Moreover, a correct meaning is judged by the association mechanism, using an original knowledge base that defines the concept of the word. The accuracy of the proposed method was 71.5%.