Definition of "greenhouse"

greenhouse

/ˈɡɹiːnˌhaʊs/

noun
plural greenhouses
1. A building used to grow plants, particularly one with large glass windows or plastic sheeting to trap heat from sunlight even in intemperate seasons or climates.
  Quotations
  The royal party had dined in the greenhouse, the coup d'œil of which was as striking as it was new. Vast stands of the most costly exotics reached to the glass roof, which was partly covered by a luxuriant vine, or by a small scarlet creeper.
  1837, L[etitia] E[lizabeth] L[andon], Ethel Churchill: Or, The Two Brides. […], volume III, London: Henry Colburn, […], pages 54–55
2. (UK military slang, dated) The glass of a plane's cockpit.
  Quotations
  In the slang of the Royal Air Force man, the cockpit of his plane is the ‘pulpit’ or ‘office’, the glass covering over it the ‘greenhouse’.
  1941 March 24, Life, page 85
3. (medicine) A structure that shields the operating table to protect against bacteria.
  Quotations
  Figure 2.6 shows the diagram Charnley published of the airflow in the 'greenhouse'; it can be seen that reasonable downward unidirectional airflow was achieved close to the operating table.
  2010, William Whyte, Cleanroom Technology
  The greenhouse system for providing a nearly bacteria-free operating environment consists of a 10 by 10-foot aluminum frame with plexiglass panes forming three sides and a polyvinyl curtain forming the fourth side. […] However, the greenhouse contains its own light supply, while this is an extra with the air curtain unit.
  1972, Southern Hospitals, volumes 40-41, page 10
4. (climatology) A hot state in global climate.
verb
third-person singular simple present greenhouses, present participle greenhousing, simple past and past participle greenhoused
1. (transitive) To place (plants) in a greenhouse.
2. (transitive, figurative) To nurture in order to promote growth.
  Quotations
  It's almost impossible to make judgements when you're being playful – as by definition it's spontaneous activity – so your baby ideas get nurtured and greenhoused better.
  2008, Chris Barez-Brown, How to Have Kick-Ass Ideas