Emily Dickinson Lexicon

REAS-ON-A-BLE-NESS, n.

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. – Law.
3. Conformity to rational principles. The whole frame and contexture of a watch carries in it reasonableness … the passive impression of the reason or intellectual idea that was in the artist. [Unusual.] – Hale.
4. Moderation; as, the reasonableness of demand.