If you have a hard time imagining an animal that enjoys munching on grass and oats also enjoying the pungent and sinus-clearing taste of horseradish, then you already, quite correctly, doubt that the name of horseradish actually refers to horses. Few animals are so adventurous as we humans, when it comes to food. Well, it so happens several English words which have horse in them, do not refer directly to the animal. Horses, of course, do not eat horseradish. The plant itself is inedible, and we only eat the root.
The word horse, in fact, is used as part of several other plant words, including horsemint, horseparsley, horsevetch, and horsechestnut. The word horse is used in this way to refer to something large and coarse, or rough. It can also have the additional connotation of strength. The term horseplay has similar origins, referring to a rough and rowdy type of playing with a lot of, uncouth, shall we say, physical contact. It is possible that horseradish, which is indeed a type of radish, may have been named in this way, so that horseradish would mean “large, course, and strong radish.”
Horseradish, a member of the same family that brings us cabbage, mustard, and radishes, has been used as an herb for thousands of years. It was grown by the Creeks and is mentioned, as well, in the Bible, being associated with the Jewish festival of Passover. In Medieval times, it was more typically used as a medicinal than a spice but it eventually began to be used as a spice, or condiment, in Europe. However, it spread from the East to the West, and England was introduced to it a bit later then Germany, in the 1500’s.
It has therefore been suggested, and judging by written sources, it is quite possible that English speakers were introduced to the root via Germany. The German word for horseradish was Meerrettich which is a compound of the words Mahre, meaning mare, or jade, and rettich meaning radish. The German word mahre, is related to the English word mare, of course, and both rettich and radish come from the Latin word radix, meaning root.
Because of the association of the original German word with a horse (a mare is an adult female horse), some etymologists believe that English speakers mistook the compound word meerrettich for two words, and translated them separately, replacing the word mare with horse. But, if this were true, we would expect to see some evidence of an earlier form of the word, mareradish, being used. We do not. Also, the origin of the meerrettich itself is disputed, and it may be that the word had nothing to do with a horse but instead was a corruption of the Latin word for horseradish, which was armoricea, meaning Armorican, or “from Brittany.”
Since the German connection seems tenuous, more credence is lent to the word horse being used the way it is used for other plants which are considered coarse, large, or strong. Horseradish roots resemble rough parsnips and their taste is somewhat like a very strong mustard (also in the same family). They are one to three inches in diameter and can grow as long as twenty inches. The pungent bite comes from an enzymatic reaction involving a sulfur-containing compound called allyl isothiocyanate. This chemical reaction occurs when the root is cut or otherwise damaged so that enzymes in the root come into contact with the compound, and can be slightly retarded by adding lemon juice or vinegar.
Allyl isothiocyanate is the same compound responsible for the irritation effects of mustard oil, and it irritates the skin, eyes, and mucous membranes to a high degree. If exposure is high enough, or the concentration is high enough, it can have toxic effects, explaining it’s use as a war gas via “mustard gas.” When inhaled it irritates and damages the airways and lungs. Conversely, at small doses it can be used as a counter-irritant, and in such remedies as mustard poultices. In horseradish, as in its relatives, this compound helps protect the plant from microorganisms, by acting to damage proteins in the organism, eventually disrupting its functions and killing the invader.
Horseradish image © Eldin Muratovic