Obsolete words not used in the dictionary are divided into two groups: archaisms and historicisms. There are certain differences between them. Archaisms included words representing objects, events, processes, and concepts; they can reflect existing and currently defined events and concepts. They are often not related to the language itself, but they can be replaced by more modern tools. The process of emergence of archaisms is called as the process of archaicization. Thus, any archaism can have a synonym in a given language.