noun (n)

• a soft yellow malleable ductile (trivalent and univalent) metallic element; occurs mainly as nuggets in rocks and alluvial deposits; does not react with most chemicals but is attacked by chlorine and aqua regia(noun.substance)

  Synonym:
  atomic number 79, gold
  

  source: wordnet30
• a unit of length used for distances within the solar system; equal to the mean distance between the Earth and the Sun (approximately 93 million miles or 150 million kilometers)(noun.quantity)

  Synonym:
  astronomical unit
  

  source: wordnet30