A buttercup is a small plant with bright yellow flowers.
buttercup in British English
(ˈbʌtəˌkʌp)
noun
any of various yellow-flowered ranunculaceous plants of the genus Ranunculus, such as R. acris (meadow buttercup), which is native to Europe but common throughout North America
See also crowfoot, goldilocks (sense 2), spearwort, lesser celandine
buttercup in American English
(ˈbʌtərˌkʌp)
adjective
1.
designating a large, widespread family (Ranunculaceae, order Ranunculales) of dicotyledonous flowering plants, includingpeonies, aconites, and anemones
noun
2.
any of a genus (Ranunculus) of normally yellow-flowered plants of the buttercup family, common in meadows and wet places