adverb (r)

• in a wasteful manner(adv.all)

  Example:
  The United States, up to the 1920s, used fuel lavishly, mainly because it was so cheap.
  

  Synonym:
  extravagantly
  

  source: wordnet30
• in a rich and lavish manner(adv.all)

  Example:
  Lavishly decorated.
  

  Synonym:
  extravagantly, richly
  

  source: wordnet30
• In a lavish manner.(adverb)

  source: webster1913