Synonyms for Cuckoo Flower (same or very similar meaning)
WordNet sense 1 (a bitter cress of Europe and America):
cuckooflower, lady's smock, Cardamine pratensis, meadow cressWordNet sense 2 (common perennial native to Europe and western Asia having usually pink flowers with ragged petals):
ragged robin, Lychins floscuculi, Lychnis flos-cuculiFrom the ODE community, based on WordNetadd/edit