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.

omentum
Folds of the peritoneum (membrane lining the abdominal cavity) that
connect the stomach with other abdominal organs.

ophthalmia neonatorum (infantile purulent conjunctivitis)