a (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;
a (n.)any of several fat-soluble vitamins essential for normal vision; prevents night blindness or inflammation or dryness of the eyes;
Synonyms: vitamin A / antiophthalmic factor / axerophthol
a (n.)(biochemistry) purine base found in DNA and RNA; pairs with thymine in DNA and with uracil in RNA;
a (n.)the basic unit of electric current adopted under the Systeme International d'Unites;
a (n.)the blood group whose red cells carry the A antigen;
Synonyms: type A / group A
a (n.)one of the four nucleotides used in building DNA; all four nucleotides have a common phosphate group and a sugar (ribose);
Synonyms: deoxyadenosine monophosphate