Various language resources employ user participation in creating a dictionary or evaluating data. An example is Thesaurus of Modern Slovene, which incorporates user participation by allowing users to suggest new synonyms and evaluate existing ones. The aim of this paper was to establish what users of the Thesaurus consider relevant synonymous data and to investigate whether users perceive synonymy differently from lexicographers and, if so, how these differences can be used to improve it. To investigate this, an evaluation of nearly 1,000 user-suggested synonyms was conducted by 42 evaluators representing 7 user groups. The focus was on cross-group analysis of the evaluation. The results showed that users evaluated synonymy differently from experts. The differences were evident in the evaluators’ comments, which gave an insight into user needs. I discussed the findings, e.g. the uneven distribution of reported issues, the need to include evaluators from different regions and age groups, or the similarities between Lexicographers and Students groups. I also addressed possible limitations and presented potential applications of the results. In conclusion, the results demonstrated both the success of the responsive model and user participation, as well as the continuing need for user studies for optimal further development of responsive dictionaries.