The BabelNet Linker is a linking web service which produces a mapping between two dictionary definitions in a cross-lingual scenario. The BabelNet-linker API allows a dictionary to be linked to BabelNet at definition level. Specifically, this API allows a definition in any language to be mapped to a semantically-equivalent English definition in BabelNet by relying on state-of-the-art Transformer-based architectures. Importantly, this API will make it possible to map the dictionaries made available within the ELEXIS Consortium at definition level by pivoting through BabelNet. BabelNet Linker was developed by the Sapienza Natural Language Processing Group (Sapienza NLP) and the ELEXIS project.