Both decomposability and transparency investigate the interplay between literality and figurativity in idioms. For this reason, they have often been merged. This study argues that idiom decomposability and transparency are related but conceptually different constructs, thus advocating for their distinction. Leveraging a normed lexicon of Italian and English idioms, the respective effects of decomposability and transparency on idiom meaning recognition are explored via statistical modeling. Results show the two variables contribute differently to idiom meaning recognition in the two languages, while the absence of collinearity underscores their distinct contributions. Based on this empirical evidence, the study finally proposes FrameNet and MetaNet as computational tools for modeling idiom decomposability and transparency. This study thus not only substantiates the separation of idiom decomposability and transparency, but also sets a foundation for future interdisciplinary research to bridge the gap in idiom research between empirical psycholinguistics, cognitive linguistics and computational applications.