Improving Retrieval-Augmented Neural Machine Translation with Monolingual Data

Maxime Bouthors, Josep Crego, Dakun Zhang, François Yvon


Abstract
Conventional retrieval-augmented neural machine translation (RANMT) systems leverage bilingual corpora, e.g., translation memories (TMs). Yet, in many settings, monolingual corpora in the target language are often available. This work explores ways to take advantage of such resources by directly retrieving relevant target language segments, based on a source-side query. For this, we design improved cross-lingual retrieval systems, trained with both sentence level and word-level matching objectives. In our experiments with two RANMT architectures, we assess of such cross-lingual objectives in a controlled setting, reaching performances that match those of standard TM-based models. We also showcase our method on real-world settings, using much larger monolingual corpora, and observe strong improvements over both the baseline setting, and general-purpose cross-lingual retrievers.
Anthology ID:
2026.eamt-1.27
Volume:
Proceedings of the 26th Annual Conference of the European Association for Machine Translation (Volume 1)
Month:
June
Year:
2026
Address:
Tilburg, The Netherlands
Editors:
Dimitar Shterionov, Eva Vanmassenhove, Mirella De Sisto, Fred Blain, Javad Pourmostafa Roshan Sharami, Lisa Lepp, Chiara Manna, Argentina Anna Rescigno, Alina Karakanta, Ayla Rigouts Terryn, Manuel Lardelli, Natalia Resende, Elena Murgolo, Janiça Hackenbuchner, Anna Zaretskaya, Miquel Esplà-Gomis, Thierry Etchegoyhen, Dagmar Gromann, Rachel Bawden, Barry Haddow, Sara Szoc, Mikel Forcada, Helena Moniz
Venue:
EAMT
SIG:
Publisher:
European Association for Machine Translation
Note:
Pages:
412–431
Language:
URL:
https://aclanthology.org/2026.eamt-1.27/
DOI:
Bibkey:
Cite (ACL):
Maxime Bouthors, Josep Crego, Dakun Zhang, and François Yvon. 2026. Improving Retrieval-Augmented Neural Machine Translation with Monolingual Data. In Proceedings of the 26th Annual Conference of the European Association for Machine Translation (Volume 1), pages 412–431, Tilburg, The Netherlands. European Association for Machine Translation.
Cite (Informal):
Improving Retrieval-Augmented Neural Machine Translation with Monolingual Data (Bouthors et al., EAMT 2026)
Copy Citation:
PDF:
https://aclanthology.org/2026.eamt-1.27.pdf