calomel
  Colorless, white or brown tasteless compound, Hg2Cl2, used as a
  purgative and insecticide.  Mercurous chloride.

cambric
  Finely woven white linen or cotton fabric.

cantharis (pl. cantharides) (also called Spanish fly)
  Brilliant green blister beetle (Lytta vesicatoria or Cantharis
  vesicatoria) of central and southern Europe.  Toxic preparation of the
  crushed, dried bodies of this beetle, formerly used as a
  counter-irritant for skin blisters and as an aphrodisiac.

capsicum
  Topical American pepper plants, genus Capsicum, especially C. annuum and
  C. frutescens.

capsid (mirid bug, mirid)
  Variety of leaf bug.

carbolic acid (phenol)
  Caustic, poisonous, white crystalline compound, C6H5Oh, derived from
  benzene and used in resins, plastics, and pharmaceuticals and in dilute
  form as a disinfectant and antiseptic.

carbuncle
  A painful localized bacterial infection of the skin that usually has
  several openings discharging pus.

cardamom
  Rhizomatous (horizontal, usually underground stem) Indian herb
  (Elettaria cardamomum) having capsular fruits with aromatic seeds used
  as a spice or condiment.  Plants of the related genus Amomum, used as a
  substitute for cardamom.

carminative
  Inducing the expulsion of gas from the stomach and intestines.

cascara (See Rhamnus purshiana)
  A buckthorn native to northwest North America; the bark yields cascara
  sagrada.

cassia
  Tropical or subtropical trees, shrubs, or herbs of the genus Cassia in
  the pea family, having yellow flowers, and long, flat or cylindrical
  pods.  Tropical Asian evergreen tree (Cinnamomum cassia) having aromatic
  bark used as a substitute for cinnamon.

Castile soap
  Fine, hard, white, odorless soap made of olive oil and sodium hydroxide.

castor oil
  Colorless or pale yellowish oil extracted from the seeds of the
  castor-oil plant, used as a laxative and skin softener.

catarrh
  Inflammation of mucous membranes, especially in the nose and throat.

catechu (cutch, Acacia catechu, betel palm)
  Spiny Asian tree with yellow flowers, and dark heartwood.  A raw material
  obtained from the heartwood of this plant, used in the preparation of
  tannins and brown dyes.

caudal
  Near the tail or hind parts; posterior.  Similar to a tail in form or
  function.

caustic potash (potassium hydroxide)
  Caustic white solid, Koh, used as a bleach and in the manufacture of
  soaps, dyes, alkaline batteries.

cerate
  Hard, unctuous, fat or wax-based solid, sometimes medicated, formerly
  applied to the skin directly or on dressings.

chambray
  Fine lightweight fabric woven with white threads across a colored warp.