bachelor's buttonsEnglishOxford New American Dictionarybachelor's buttons /ˈˌbaCH(ə)lərz ˌbətnz, ˈˌbætʃ(ə)lərz ˌbətnz/ ▸ plural noun [treated as singular or plural] any of a number of ornamental plants that bear small double flowers. ● a white flower of the daisy family (Achillea ptarmica, family Compositae). ● a yellow buttercup (Ranunculus acris, family Ranunculaceae).