as

n a very poisonous metallic element that has three allotropic forms; arsenic and arsenic compounds are used as herbicides and insecticides and various alloys; found in arsenopyrite and orpiment and realgar n a United States territory on the eastern part of the island of Samoa n a metric unit of length equal to one ten billionth of a meter (or 0.0001 micron); used to specify wavelengths of electromagnetic radiation n any of several fat-soluble vitamins essential for normal vision; prevents night blindness or inflammation or dryness of the eyes n one of the four nucleotides used in building DNA; all four nucleotides have a common phosphate group and a sugar (ribose) n (biochemistry) purine base found in DNA and RNA; pairs with thymine in DNA and with uracil in RNA n the basic unit of electric current adopted under the Systeme International d'Unites n the 1st letter of the Roman alphabet n the blood group whose red cells carry the A antigen r to the same degree (often followed by `as')