shamrock
noun
°The trefoil leaf of any small clover, especially Trifolium repens, or such a leaf from a clover-like plant.
"She wore a shamrock in honor of her Irish ancestry."
°Any of several small plants, forms of clover, with trefoil leaves, especially Trifolium repens.
"The fields were covered with shamrocks."
synonyms: trefoil, clover