copperas (ferrous sulfate)
Greenish crystalline compound, FeSO4.7H2O, used as a pigment,
fertilizer, and feed additive, in sewage and water treatment, and in the
treatment of iron deficiency.

corrosive sublimate
Mercuric chloride.

costal
Relating to or near a rib.

costive
Constipated

cranesbill (geranium, storksbill) Plants of the genus Geranium, with pink or purplish flowers. Various plants of the genus Pelargonium, native chiefly to southern Africa and widely cultivated for their rounded and showy clusters of red, pink, or white flowers.

cream of tartar
Potassium bitartrate. White, acid, crystalline solid or powder,
KHC4H4O6, used in baking powder, in the tinning of metals, and as a
laxative.

Creasote (creosote)
Colorless to yellowish oily liquid containing phenols and creosols,
obtained by the destructive distillation of wood tar, especially from
beech, and formerly used as an expectorant in treating chronic
bronchitis. Also used as a wood preservative and disinfectant. May cause
severe neurological disturbances if inhaled.

crepe de Chine
Silk crepe used for dresses and blouses.

cretonne
Heavy unglazed cotton, linen, or rayon fabric, colorfully printed and
used for draperies and slipcovers.

croton oil
Brownish-yellow, foul-smelling oil from the seeds of a tropical Asian
shrub or small tree (Croton tiglium); formerly used as a drastic
purgative and counterirritant. Its use was discontinued because of its
toxicity.