1. Historically: A tribute formerly extracted from farmers and small owners in the border counties of England and Scotland, and along the Highland border, by freebooting chiefs, in return for protection or immunity from plunder.
2. By extension: Any payment extorted by intimidation or pressure, or levied by unprincipled officials, critics, journalists, etc. upon those whom they have it in their power to help or injure. Now usually a payment extorted by threats or pressure, especially by threatening to reveal a discreditable secret.
The Oxford English Dictionary, via.
1. Historically: a file kept by government officials to blackmail or destroy friends and enemies alike.
2. By extension: secret files or watch lists on protesters and other chronic malcontents kept by government bureaus, secret services, private contractors, paramilitaries, telephone companies, internet service providers, employers, libraries, and other entities to assist the duly constituted authorities in keeping things under control for the benefit of all concerned, with none the wiser.
Philanthropy and/or Voluntary Action for Social Change
1. Historically: an ineffectual effort by dupes to change a world owned and controlled by knaves.
2. By extension: Any subversive activity which by means of philanthropy, social organizing, satire, expose, meditation, prayer, or peaceful protest attempts to turn the world upside down, or right side up, depending which side you are on.