Synonyms for Kingcup (same or very similar meaning)
WordNet sense 1 (swamp plant of Europe and North America having bright yellow flowers resembling buttercups):
cowslip, marsh marigold, Caltha palustris, May blob, meadow bright, water dragonWordNet sense 2 (any of various plants of the genus Ranunculus):
buttercup, crowfoot, butterflower, butter-flower, goldcupFrom the ODE community, based on WordNetadd/edit