This paper describes the creation of a normed lexicon of 150 pairs of English and Italian idioms annotated by translatability level (Beck, 2020). The dataset was created through the implementation of a cross-linguistic norming study conducted online via a novel combination of tools and design, which was validated by data reliability measurement. The lexicon contains information with respect to two groups of idiom variables (Hubers, Cucchiarini, Strik, & Dijkstra, 2019): Experience-Based Variables ("EBVs": familiarity, meaningfulness and objective knowledge) and Content-Based Variables ("CBVs": literal plausibility, decomposability and transparency). These variables are particularly relevant for the analysis of ambiguous contexts where there is an interaction between the literal and figurative meaning of an idiom (Wagner, 2021). In particular, the sum of the mean ratings obtained for the three CBVs provides the Potential Idiomatic Ambiguity ("PIA") index of each idiom: the higher the PIA, the more likely the idiom should be to occur in ambiguous contexts. This index can therefore be exploited in the setup of future psycholinguistic experiments to verify the relationship between the internal distribution of idiom features and ambiguous contexts. Moreover, the lexicon is a valuable research tool per se, since it contributes to bridging the gap in cross-linguistic research in idiom norming studies (Nordmann, Cleland, & Bull, 2014;Pastor, 2021), enabling systematic comparative analyses and enhancing understanding of the relationships among the examined variables.