a metric unit of length equal to one billionth of a meter | the blood group whose red cells carry the A antigen |
| the 1st letter of the Roman alphabet |
| the basic unit of electric current adopted under the Systeme International d'Unites |
| a metric unit of length equal to one ten billionth of a meter (or 0.0001 micron); used to specify wavelengths of electromagnetic radiation |
| any of several fat-soluble vitamins essential for normal vision; prevents night blindness or inflammation or dryness of the eyes |
| one of the four nucleotides used in building DNA, also known as deoxyadenylate, or dAMP; all four nucleotides have a common phosphate group and a sugar (ribose) |
| (biochemistry) purine base found in DNA and RNA; pairs with thymine in DNA and with uracil in RNA |