horseradish - grated horseradish root

Armoracia rusticana, horse radish, red cole, horseradish - coarse Eurasian plant cultivated for its thick white pungent root

root - (botany) the usually underground organ that lacks buds or leaves or nodes; absorbs water and mineral salts; usually it anchors the plant to the ground

isothiocyanate - a family of compounds derived from horseradish and radishes and onions and mustards; source of the hotness of those plants and preparations