meatus
  Body opening or passage, such as the opening of the ear or the urethra.

menorrhagia
  Unusually heavy or extended menstrual flow.

menstruum
  Solvent used to extract compounds from plant and animal tissues and
  preparing drugs.

messaline
  Lightweight, soft, shiny silk cloth with a twilled or satin weave.

mezereon
  Poisonous Eurasian ornamental shrub (Daphne mezereum) with fragrant
  lilac-purple flowers and small scarlet fruit.  The dried bark of this
  plant was used externally as a vesicant (blistering agent) and
  internally for arthritis.

miliary
  Appearance of millet seeds.  Small skin lesions with the appearance of
  millet seeds.

mullein
  Eurasian plants of the genus Verbascum, especially V. thapsus.  Also
  called flannel leaf, velvet plant.

muriate
  Chloride; compound of chlorine with another element or radical;
  especially, a salt or ester of hydrochloric acid called.

myrrh
  Aromatic gum resin from trees and shrubs of the genus Commiphora of
  India, Arabia, and eastern Africa, used in perfume and incense.

methyl salicylate
  Liquid ester C8H8O3 obtained from the leaves of wintergreen (Gaultheria
  procumbens) or the bark of a birch (Betula lenta); now made
  synthetically, and used as a flavoring and a counterirritant.

motherwort
  Eurasian plants of the genus Leonurus, especially L. cardiaca, a weed
  having clusters of small purple or pink flowers.

mugwort
  Aromatic plants of the genus Artemisia, especially A. vulgaris, native
  to Eurasia; used as a condiment.

mustard plaster (sinapism)
  Medicinal plaster made with a paste-like mixture of powdered black
  mustard, flour, and water, used as a counterirritant.

nephritis
  Various acute or chronic inflammations of the kidneys, such as Bright’s
  disease.

naphthalene (naphthaline, tar camphor)
  White crystalline compound, C10H8, derived from coal tar or petroleum
  and used in manufacturing dyes, moth repellents, and explosives and as a
  solvent.

nebulize
   To convert a liquid to a fine spray; atomize. 
   To treat with a medicated spray.

nainsook
  Soft lightweight muslin used for babies.

Neroli
  An essential oil made by distilling the flowers of the orange; it is
  used in perfume.

nitre (niter, saltpeter)
  Potassium nitrate, KNO3, used in making gunpowder.

nux vomica
  Tree (Strychnos nux-vomica) native to southeast Asia, having poisonous
  seeds that are the source of the medicinal alkaloids strychnine and
  brucine.

ocher (ochre)
  Yellow, brown, or red mineral oxides of iron used as pigments.

oil of vitriol
  Sulfuric acid; highly corrosive, dense, oily liquid, H2so4, colorless to
  dark brown depending on its purity and used to manufacture a wide
  variety of chemicals and materials including fertilizers, paints,
  detergents, and explosives.