noun (n)

• a state of being relaxed and feeling no pain(noun.state)

  Example:
  She longed for the comfortableness of her armchair.
  

  Synonym:
  comfort
  Antonym:
  discomfort, uncomfortableness
  

  source: wordnet30
• a feeling of being at ease in a relationship(noun.feeling)

  source: wordnet30
• State of being comfortable.(noun)

  source: webster1913