verb (v)

• cause (a liquid) to enter by penetrating the interstices(verb.motion)

  source: wordnet30
• enter a group or organization in order to spy on the members(verb.social)

  Example:
  The student organization was infiltrated by a traitor.
  

  Synonym:
  penetrate
  

  source: wordnet30
• pass into or through by filtering or permeating(verb.motion)

  Example:
  The substance infiltrated the material.
  

  source: wordnet30
• pass through an enemy line; in a military conflict(verb.motion)

  Synonym:
  pass through
  

  source: wordnet30
• To enter by penetrating the pores or interstices of a substance; to filter into or through something.(verb)

  source: webster1913
• To penetrate gradually; -- sometimes used reflexively.(verb)

  source: webster1913