pyrethrum: white-flowered pyrethrum of Balkan area whose pinnate leaves are white and silky-hairy below; source of an insecticide; sometimes placed in genus Chrysanthemum
herb: a plant lacking a permanent woody stem; many are flowering garden plants or potherbs; some having medicinal properties; some are pests
hodgkin's disease: a malignant disorder in which there is progressive (but painless) enlargement of lymph tissue followed by enlargement of the spleen and liver