agreeableness

1. The quality of being agreeable or pleasing; that quality which gives satisfaction or moderate pleasure to the mind or senses.

That author . . . has an agreeableness that charms us.

2. The quality of being agreeable or suitable; suitableness or conformity; consistency.

The agreeableness of virtuous actions to human nature.

3. Resemblance; concordance; harmony; -- with to or between. [Obs.]

The agreeableness between man and the other parts of the universe.

noun

The quality of being pleasant and friendly: affability, agreeability, amenity, amiability, amiableness, congeniality, congenialness, cordiality, cordialness, friendliness, geniality, genialness, pleasantness, sociability, sociableness, warmth. See attitude/good attitude/bad attitude/neutral attitude, good/bad.

The noun has 2 meanings:

Meaning #1: pleasantness resulting from agreeable conditions
  Synonym: amenity
  Antonym: disagreeableness (meaning #1)

Meaning #2: a temperamental disposition to be agreeable
  Synonym: agreeability
  Antonym: disagreeableness (meaning #2)