GREENHOUSE

[noun] [C] [plural] greenhouses - a building with a roof and sides made of glass, used for growing plants that need warmth and protectionGladys grows a lot of tomatoes in her greenhouse.The greenhouse effect is an increase in the amount of carbon dioxide and other gases in the atmosphere which is believed to be the cause of a gradual warming of the surface of the Earth. A greenhouse gas is a gas which causes the greenhouse effect, esp. carbon dioxide.