adverb (r)

• to a small degree or extent(adv.all)

  Example:
  The children argued because one slice of cake was slightly larger than the other.
  

  source: wordnet30
• in a slim or slender manner(adv.all)

  Example:
  Slightly built.
  

  Synonym:
  slenderly, slimly
  

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

  source: webster1913