Other forms: greenhouses
A greenhouse is the glass building where plants are grown warm all year. A greenhouse tomato, in the greenhouse, heat the greenhouse.
It works by letting sunlight in and trapping the heat that would otherwise escape. That is the mechanism behind the greenhouse effect, which is why the phrase is used for the warming of the atmosphere, and greenhouse gases are the ones that trap it — carbon dioxide, methane, nitrous oxide. Note glasshouse, the older British word, and conservatory, which is attached to a house and meant for people.
1noungreenhouseA glass building where plants are grown.
“My grandfather grows tomatoes and cucumbers in his greenhouse.”
greenhouse is a building for plants.
The word is a plain compound of green and house, first recorded in the seventeenth century when heated glass buildings became possible. Green here means the plants rather than the colour of the glass.
From green + house "house for growing greens", in reference to the produce grown within.
Etymology from Wiktionary, CC BY-SA