■ plural noun [treated as sing. or plural ] an ornamental plant with small, button-like, double flowers. [ Achillea ptarmica (daisy family) and Ranunculus acris (buttercup family).]
BACHELOR'S BUTTONS
Meaning of BACHELOR'S BUTTONS in English
Concise Oxford English vocab. Сжатый оксфордский словарь английского языка. 2004