Culpeper placed horehound under Mercury, the ruler of the breath and the airy passages, which fitted its long reputation as a herb for the chest. In folk magic its intense bitterness gave it a protective and counter-magical role: horehound was used to break spells and to guard against sorcery, and classical writers list it among the plants that dispel enchantment. Its meanings, clearing, protection, the breaking of harm, follow directly from its two plain properties, a piercing bitterness and a clearing effect on the breath. A homely, hardy, unglamorous herb, horehound carries an old and consistent reputation as a plant of protection and relief.
Dioscorides, the first-century Greek physician whose materia medica shaped western herbalism for over a thousand years, recommended horehound specifically against the bites of venomous creatures as well as for coughs, a double reputation, poison and protection, that matches its later folk role as a herb that broke curses and turned back harm. The plant's Latin genus name, Marrubium, is of obscure and disputed origin, variously traced to a Hebrew word for a bitter juice or to an old Italian place name, a small case where even its formal scientific name carries an unresolved etymological question.