*incubator*

n. 1. That which incubates, especially, an apparatus by means of which eggs are hatched by artificial heat. [ 1913 Webster ]

2. An apparatus containing an enclosed chamber, used for the cultivation of microörganisms or tissue cultures by maintaining a suitable temperature and atmospheric composition. Some incubators have no provision for maintaining a special atmosphere, while in others, especially for anaerobic organisms and tissue culture, the moisture level and composition of the gases are also controlled. [ Webster 1913 Suppl. +PJC ]

3. (Med.) An apparatus consisting of enclosed chamber, for maintaining prematurely born babies in a favorable environment until able to thrive under normal conditions. The temperature and level of oxygen in the atmosphere may be controlled. [ Webster 1913 Suppl. +PJC ]