Definition-Guided Learning and Root-Stratified Evaluation for Arabic Lexical Semantics

Samar Ahmad, Abdullah I. Alharbi, Omer Nacar, Shahad Altamimi, Yahya Assiri


Abstract
We introduce Definition-Guided Learning (DGL), a contrastive training framework that uses dictionary definitions as semantic queries and lemmas as retrieval targets, instantiated here for Arabic reverse dictionary retrieval. We construct a root-stratified Arabic lexical benchmark that limits morphological root overlap between training and test partitions. Zero-shot evaluation suggests a notable gap, with the best pre-trained model achieving only 11.16% Top@1 accuracy on this benchmark. Fine-tuning with DGL yields 41.13% Top@1 and NDCG@10 of 49.32%, an improvement of roughly 3.7 times over the strongest zero-shot baseline we tested. Our results suggest that in-batch negative sampling tends to outperform Triplet Loss in this setting, and that definition length and lexical difficulty appear to trade off in importance across retrieval depth. These findings offer preliminary evidence that lexicographic resources can serve as a useful supervisory signal for Arabic embedding learning, at least within the scope of the benchmark studied here.
Anthology ID:
2026.arabicnlp-main.29
Volume:
Proceedings of The Fourth Arabic Natural Language Processing Conference
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Muhammad Abdul-Mageed, Tamer Elsayed, Houda Bouamor, Samhaa El-Beltagy, Hend Al-Khalifa, Ahmed Abdelali, AbdelRahim Elmadany, Abdellah El Mekki, Kareem Darwish, Sakhar Alkhereyf, Hamzah Luqman, Salam Khalifa, Samar Magdy, Zaid Alyafeai, Injy Hamed, Wajdi Zaghouani, Imed Zitouni
Venue:
ArabicNLP
SIG:
SIGARAB
Publisher:
Association for Computational Linguistics
Note:
Pages:
418–432
Language:
URL:
https://aclanthology.org/2026.arabicnlp-main.29/
DOI:
Bibkey:
Cite (ACL):
Samar Ahmad, Abdullah I. Alharbi, Omer Nacar, Shahad Altamimi, and Yahya Assiri. 2026. Definition-Guided Learning and Root-Stratified Evaluation for Arabic Lexical Semantics. In Proceedings of The Fourth Arabic Natural Language Processing Conference, pages 418–432, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Definition-Guided Learning and Root-Stratified Evaluation for Arabic Lexical Semantics (Ahmad et al., ArabicNLP 2026)
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PDF:
https://aclanthology.org/2026.arabicnlp-main.29.pdf