Earmarks - OMB site
What is an Earmark?
Earmarks are funds provided by the Congress for projects or programs where the congressional direction (in bill or report language) circumvents the merit-based or competitive allocation process, or specifies the location or recipient, or otherwise curtails the ability of the Executive Branch to properly manage funds. Congress includes earmarks in appropriation bills - the annual spending bills that Congress enacts to allocate discretionary spending - and also in authorization bills.
http://www.sourcewatch.org/ "Earmarking" is the term used to refer to a provision in legislation that directs funds to be spent on specific projects. Typically, legislators seek to insert earmarks which direct a specified amount of money to a particular organization or project in his/her home state or district. This differs from the appropriation of money to a particular government agency, for in these cases the appropriate executive department can exercise discretion as to where and how the funds are spent. The use of earmarks in the U.S. Congress has expanded significantly over the past thirty years, and is presently the focus of much controversy.