horse·rad·ish 
(hôrsrăd′ĭsh)
(hôrsrăd′ĭsh)n.
1.
a. A coarse Eurasian plant (Armoracia rusticana) in the mustard family, having a thick, whitish, pungent root, large basal leaves, and white flowers in a terminal panicle.
b. The roots of this plant.
2.
a. A sharp condiment made from the grated roots of this plant.
b. Any of various pungent condiments resembling horseradish, such as wasabi.