oat cell carcinoma: highly malignant carcinoma composed of small round or egg-shaped cells with little cytoplasm; lung cancers are frequently oat cell carcinomas
malignancy: (medicine) a malignant state; progressive and resistant to treatment and tending to cause death
mexican hat: coneflower with flower heads resembling a Mexican hat with a tall red-brown disk and drooping yellow or yellow and red-brown rays; grows in the great plains along base of Rocky Mountains