Ethnic cleansing is the systematic elimination of unwanted ethnic group(s) from a region or society by one or more of the following methods:
In its original language Serbian/Croation the expression is 'etničko čišćenje' and was used by former Yugoslav Peoples Army governed by Slobodan Milosevic. So it could be deduced that it was initially part of former Yugoslav military terminology.
The term became more widely used in Kosovo around 1981 after mass media reports discussed the establishment of 'Ethnically clean territories'. Initially it described the non-violent treatment of the Serbian minority by the Kosovo Albanians in the independent region within the Socialist Federal Republic of Yugoslavia.
However the war in Bosnia and Herzegovina helped journalists, politicians and UN institutions coin the term Ethnic Cleansing to describe violation of human rights and humanitarian law which was at the time occurring in Bosnia, Herzegovina and Croatia.
http://www.ejil.org/journal/Vol5/No3/art3.html#TopOfPage
http://www.cnn.com/2001/WORLD/europe/03/30/milosevic.profile/
http://www.infoplease.com/ipd/A0429476.html
http://www.bartleby.com/61/89/E0228950.html