a tall herb (Foeniculum vulgare) of the umbel family, with feathery leaves and yellow flowers: its foliage and aromatic seeds are used to flavor foods and medicines
See fennel in American Heritage Dictionary 4
(fĕnˈəl)
noun
A Eurasian plant (Foeniculum vulgare) having pinnate leaves, clusters of small yellow flowers grouped in umbels, and aromatic seeds used as flavoring.