Evaluating Lexical Proficiency in Neural Language Models

Cristiano Ciaccio, Alessio Miaschi, Felice Dell’Orletta


Abstract
We present a novel evaluation framework designed to assess the lexical proficiency and linguistic creativity of Transformer-based Language Models (LMs). We validate the framework by analyzing the performance of a set of LMs of different sizes, in both mono- and multilingual configuration, across tasks involving the generation, definition, and contextual usage of lexicalized words, neologisms, and nonce words. To support these evaluations, we developed a novel dataset of lexical entries for the Italian language, including curated definitions and usage examples sourced from various online platforms. The results highlight the robustness and effectiveness of our framework in evaluating multiple dimensions of LMs’ linguistic understanding and offer an insight, through the assessment of their linguistic creativity, on the lexical generalization abilities of LMs.
Anthology ID:
2025.acl-long.64
Volume:
Proceedings of the 63rd Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Month:
July
Year:
2025
Address:
Vienna, Austria
Editors:
Wanxiang Che, Joyce Nabende, Ekaterina Shutova, Mohammad Taher Pilehvar
Venue:
ACL
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
1267–1286
Language:
URL:
https://preview.aclanthology.org/ingestion-acl-25/2025.acl-long.64/
DOI:
Bibkey:
Cite (ACL):
Cristiano Ciaccio, Alessio Miaschi, and Felice Dell’Orletta. 2025. Evaluating Lexical Proficiency in Neural Language Models. In Proceedings of the 63rd Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers), pages 1267–1286, Vienna, Austria. Association for Computational Linguistics.
Cite (Informal):
Evaluating Lexical Proficiency in Neural Language Models (Ciaccio et al., ACL 2025)
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PDF:
https://preview.aclanthology.org/ingestion-acl-25/2025.acl-long.64.pdf