reasonableness

Concise Oxford English Dictionary © 2008 Oxford University Press:
reasonable/ˈriːznəbl/

▶adjective

• 1 fair and sensible.

• 2 archaic able to reason logically.

• 3 as much as is appropriate or fair; moderate.

  ■ fairly good.

  ■ relatively inexpensive.

– derivatives
reasonableness noun,
reasonably adverb.

– origin ME: from OFr. raisonable, suggested by L. rationabilis ‘rational’, from ratio (see reason).