The Polish WordNet is a network of lexical-semantic relations, an electronic thesaurus with a structure modelled on that of the Princeton WordNet and those constructed in the EuroWordNet project. Polish WordNet describes meaning of a lexical unit by placing it within a network of semantic relations, such as hypernyny, meronymy, antonymy etc. To reduce the cost of the project, Polish WordNet has been built semi-automatically. Lexical relations were automatically recognized in large corpora of Polish and suggested to linguists/lexicographers via a graphical interface. Nowadays Polish WordNet is one of the biggest wordnets in the world; it comprises 103000 lexical units in 74000 synsets. The current version of the resource introduces 5500 relations between synsets of plWordNet and Princeton WordNet.