There are many research activities concerning Linked Data, but Lined Data are not actively utilized for many purposes. One of the reasons is that it is not easy to express various kinds of information as Linked Data. Another reason is a lack of standard vocabularies for many domains. It is also desirable to specify the meaning of vocabularies in a formal way so that the meaning of Linked Data can be processed automatically. This paper proposes a method for specifying the meaning of vocabularies (in particular, predicates) used in Linked Data by using object-oriented modeling technologies and a formal specification language. With this method, standard vocabularies, with a formal specification of their meaning, can be generated for many domains, and the meaning of Linked Data generated with these vocabularies can be processed automatically to some extent.