horseradish vs horse radish

horseradish and horse radish both are nouns.

Word	Noun	Adjective	Verb	Adverb
horseradish	Yes	No	No	No
horse radish	Yes	No	No	No

As nouns, horseradish and horse radish are synonyms defined as:

horseradish and horse radish: coarse Eurasian plant cultivated for its thick white pungent root

Other synonyms of horseradish include Armoracia rusticana, red cole.

horseradish (noun)	horse radish (noun)
grated horseradish root	coarse Eurasian plant cultivated for its thick white pungent root
coarse Eurasian plant cultivated for its thick white pungent root
the root of the horseradish plant; it is grated or ground and used for seasoning