AbstractThe results of manual mapping of Polish plWordNet onto English Princeton WordNet revealed a number of gaps and mismatches between those interlinked lexical resources. Preliminary studies have shown that they embrace wordnet-specific and language-specific differences, and in this exploratory study we focus on the latter, also called lacunae. Capitalising on the system of equivalence types and features for linking wordnet senses (Rudnicka et al. 2019), we present a semi-automatic, rule-based diagnostic system developed specifically for systematic detection and classification of gaps and mismatches between wordnets. First, focusing on noun synsets, we aim to identify those network fragments that are the most prone to reveal lexical and referential gaps (Svensén 2009). Second, we attempt to identify areas in an interlinked Polish-English wordnet that require resource expansion or modification of the existing network of inter-lingual relations.