1. in a manner that expresses doubt, hesitation, or conditional acceptance; not completely or wholeheartedly
I agree with the proposal, but with reservation about the timeline.
Concordo com a proposta, mas com ressalva quanto ao cronograma.
2. while maintaining some conditions, limitations, or qualifications to a statement or agreement
The expert endorsed the study with reservation regarding its methodology.
O especialista endossou o estudo com ressalva quanto à sua metodologia.