1. The faculty of reason. [In this sense, little used.]
2. Agreeableness to reason; that state or quality of a thing which reason supports or justifies; as the reasonableness of our wishes, demands or expectations.
the reasonableness and excellency of charity.
3. Conformity to rational principles.
The whole frame and contexture of a watch carries in it a reasonableness - the passive impression of the reason or intellectual idea that was in the artist. [Unusual.]
4. Moderation; as the reasonableness of a demand.