1. maintenance of baby in controlled environment: the keeping of a premature or unwell baby in an environment in which the temperature, humidity, and oxygen levels can be easily controlled
2. controlled growth of microorganisms: the maintenance of cells or microorganisms under a controlled temperature in or on a medium so that they can multiply
3. growth of disease-causing microorganisms: the development of an infection inside the body to the point at which the first signs of disease become apparent
4. gradual development: the slow development of something, especially through thought and planning
