noun (n)

• an increase in the density of something(noun.event)

  Synonym:
  compaction, concretion, densification
  

  source: wordnet30
• the process or result of becoming smaller or pressed together(noun.event)

  Synonym:
  condensation, contraction
  

  source: wordnet30
• encoding information while reducing the bandwidth or bits required(noun.act)

  Antonym:
  decompression
  

  source: wordnet30
• applying pressure(noun.act)

  Synonym:
  compressing
  Antonym:
  decompressing, decompression
  

  source: wordnet30
• The act of compressing, or state of being compressed.(noun)

  source: webster1913