noun (n)

• the act of increasing (something) in size or volume or quantity or scope(noun.act)

  Synonym:
  enlargement
  Antonym:
  contraction
  

  source: wordnet30
• a function expressed as a sum or product of terms(noun.linkdef)

  Example:
  The expansion of (a+b)^2 is a^2 + 2ab + b^2.
  

  source: wordnet30
• a discussion that provides additional information(noun.communication)

  Synonym:
  elaboration, enlargement
  

  source: wordnet30
• adding information or detail(noun.act)

  Synonym:
  expanding upon
  

  source: wordnet30
• The act of expanding or spreading out; the condition of being expanded; dilation; enlargement.(noun)

  source: webster1913