The program Synarcher for synonym (and related terms) search in the text corpus of special structure (Wikipedia) was developed. The results of the search are presented in the form of graph. It is possible to explore the graph and search for graph elements interactively. Adapted HITS algorithm for synonym search, program architecture, and program work evaluation with test examples are presented in the paper. The proposed algorithm can be applied to a query expansion by synonyms (in a search engine) and a synonym dictionary forming.