Word Study
hippeastrum
CIDE DICTIONARY
hippeastrum, n.
An amaryllis of tropical America (Hippeastrum puniceum ) often cultivated as a houseplant for its showy white to red flowers. [WordNet 1.5]
OXFORD DICTIONARY
hippeastrum, n. any S. American bulbous plant of the genus Hippeastrum with showy white or red flowers.
Etymology
mod.L f. Gk hippeus horseman (the leaves appearing to ride on one another) + astron star (from the flower-shape)
For further exploring for "hippeastrum" in Webster Dictionary Online