One and the same query can be formulated in many different ways. For example, the queries like "how to deduce the address from the telephone number", "search for address by telephone number", and "find an address by telephone number" have the same meaning for the user, these are synonymous queries.

A number of different practices leads to synonymous queries. Among them:
- using the well-knwon abbreviations: "weather in Saint Petersburg" and "weather in SpB";
- using transliteration – "gazeta ru website" and "газета ру website";
- varying word order - "repair automatic transmission" and "automatic transmission repair"

In most of these cases, the users expect to get information related to the meaning of the query, not to its particular formulation. We can take this to imply that the search engines should yield identical results in response to synonymous queries, despite the differences in query formulation.

The analyzer of the synonymous queries assesses the (presumably unnecessary) variability of responses to synonymous queries. The search engines are sorted by the amount of such variability.

All the queries used in this analyzer are real, they were acquired from Rambler's query statistics tool (http://adstat.rambler.ru/wrds/). Note also that we are excluding the queries containing grammatical or spelling errors from this analyzer.