The existing usage of expressions in language is not unique, but technical terms do not show synonyms as much as in natural languages. People with the same education and language know or use the same expressions. A `worlds language' does not prevent the problem of uniqueness because it has to be standardized before spread around the world. This is the case with natural languages (such as English) as with planed languages (as Esperanto). Terminology should not be influenced by language change unconsciously.