noun (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(noun.quantity)

  Synonym:
  angstrom, angstrom unit
  

  source: wordnet30
• any of several fat-soluble vitamins essential for normal vision; prevents night blindness or inflammation or dryness of the eyes(noun.substance)

  Synonym:
  antiophthalmic factor, axerophthol, vitamin a
  

  source: wordnet30
• one of the four nucleotides used in building DNA; all four nucleotides have a common phosphate group and a sugar (ribose)(noun.substance)

  Synonym:
  c, deoxyadenosine monophosphate, deoxycytidine monophosphate, deoxyguanosine monophosphate, deoxythymidine monophosphate, g, t
  

  source: wordnet30
• (biochemistry) purine base found in DNA and RNA; pairs with thymine in DNA and with uracil in RNA(noun.substance)

  Synonym:
  adenine
  

  source: wordnet30
• the basic unit of electric current adopted under the Systeme International d'Unites(noun.quantity)

  Example:
  A typicAl household circuit cArries 15 to 50 Amps.
  

  Synonym:
  amp, ampere
  

  source: wordnet30
• the 1st letter of the Roman alphabet(noun.communication)

  source: wordnet30
• the blood group whose red cells carry the A antigen(noun.body)

  Synonym:
  group a, type a
  

  source: wordnet30