hotbed

Etymology

hot +‎ bed

Noun

hotbed (plural hotbeds)

1. a low bed of earth covered with glass, and heated with rotting manure; used for the germination of seeds and the growth of tender plants. A hotbed works as a miniature hothouse, i.e. greenhouse.
2. (by extension) an environment that is ideal for the growth or development of something, especially of something undesirable
3. An iron platform in a rolling mill, on which hot bars, rails, etc., are laid to cool.