1. A translation method for translating a source text in a given source language input into a computer into a text in a target language, comprising the steps of: extracting an unregistered word that is not registered in a database referenceable to said computer; if said extracted unregistered word contains two or more successive identical characters, generating a modified word from said unregistered word by reducing the number of the successive identical characters; and translating said source text with reference to said database with replacing said unregistered word in said source text with said modified word.