Nahw: A Comprehensive Benchmark of Arabic Grammar Understanding, Error Detection, Correction, and Explanation

Hamdy Mubarak, Majd Hawasly, Abubakr Mohamed


Abstract
Grammar comprehension is a critical capability for large language models (LLMs) to achieve fluency in a target language. In low-resource settings, such as the case with Arabic, limited availability of high-quality data can lead to significant gaps in grammatical understanding, making systematic evaluation essential. We introduce Nahw, a comprehensive benchmark for Arabic grammar that covers both theoretical knowledge and practical applications, including grammatical error detection, correction, and explanation. We evaluate a range of LLMs on these tasks and find that many models still exhibit substantial deficiencies in Arabic grammar comprehension, with GPT-4o achieving a score of 67% on average over all tasks, while the best performing Arabic model in our experiment (ALLaM-7B) achieving 42%. Our experiments also demonstrate that while fine-tuning with synthetic data can improve performance, it does not match the effectiveness of training on natural, high-quality data.
Anthology ID:
2026.eacl-long.296
Volume:
Proceedings of the 19th Conference of the European Chapter of the Association for Computational Linguistics (Volume 1: Long Papers)
Month:
March
Year:
2026
Address:
Rabat, Morocco
Editors:
Vera Demberg, Kentaro Inui, Lluís Marquez
Venue:
EACL
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
6310–6328
Language:
URL:
https://preview.aclanthology.org/ingest-eacl/2026.eacl-long.296/
DOI:
Bibkey:
Cite (ACL):
Hamdy Mubarak, Majd Hawasly, and Abubakr Mohamed. 2026. Nahw: A Comprehensive Benchmark of Arabic Grammar Understanding, Error Detection, Correction, and Explanation. In Proceedings of the 19th Conference of the European Chapter of the Association for Computational Linguistics (Volume 1: Long Papers), pages 6310–6328, Rabat, Morocco. Association for Computational Linguistics.
Cite (Informal):
Nahw: A Comprehensive Benchmark of Arabic Grammar Understanding, Error Detection, Correction, and Explanation (Mubarak et al., EACL 2026)
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PDF:
https://preview.aclanthology.org/ingest-eacl/2026.eacl-long.296.pdf