noun (n)

• maintaining something at the most favorable temperature for its development(noun.act)

  source: wordnet30
• (pathology) the phase in the development of an infection between the time a pathogen enters the body and the time the first symptoms appear(noun.time)

  source: wordnet30
• sitting on eggs so as to hatch them by the warmth of the body(noun.process)

  Synonym:
  brooding
  

  source: wordnet30
• A sitting on eggs for the purpose of hatching young; a brooding on, or keeping warm, (eggs) to develop the life within, by any process.(noun)

  source: webster1913