noun (n)

• an insulating liner in an opening through which conductors pass(noun.artifact)

  source: wordnet30
• a cylindrical metal lining used to reduce friction(noun.artifact)

  Synonym:
  cylindrical lining
  

  source: wordnet30
• The operation of fitting bushes, or linings, into holes or places where wear is to be received, or friction diminished, as pivot holes, etc.(noun)

  source: webster1913