a garden of evergreen plants and plants that flower in winter
2.
a conservatory in which flowers are grown in winter
winter garden in American English
noun
1.
an outdoor garden maintained during the winter with hardy plants
2.
a conservatory devoted to the cultivation of winter-blooming plants
Word origin
[1775–85]This word is first recorded in the period 1775–85. Other words that entered Englishat around the same time include: alto, backfire, guideline, pinafore, waltz