1. A computer system for building concept knowledge from a machine-readable dictionary, comprising a machine-readable dictionary including a plurality of words in a first language and a plurality of corresponding translated words in a second language, and a plurality of words in the second language and a plurality of corresponding translated words in the first language; an input device for inputting a seed word; a forward-translator for obtaining a plurality of translated words in the second language corresponding to said seed word by looking up said machine-readable dictionary; and a backward-translator for obtaining a plurality of translated words in the first language corresponding to each of said plurality of translated words obtained by said translator respectively as words of the concept knowledge, by looking up said machine-readable dictionary.