Source : Webster's Revised Unabridged Dictionary (1913)

Incubator \In"cu*ba`tor\, n.
   That which incubates, especially, an apparatus by means of
   which eggs are hatched by artificial heat.

Incubator \In"cu*ba`tor\, n.
   1. A contrivance for the cultivation of micro["o]rganisms by
      maintaining a suitable temperature.

   2. (Med.) An apparatus for rearing prematurely born babies.

Source : WordNet®

incubator
     n : apparatus consisting of a box designed to maintain a
         constant temperature by the use of a thermostat; used for
         chicks or premature infants [syn: {brooder}]