What is "sil'hooettes"

The Virginia Sil'hooettes is a student-run, all-female a cappella group at the University of Virginia in Charlottesville, VA. Once just the vision of four UVa students in the winter of 1988, the Sil'hooettes are now the most award-winning women's group at UVa. The Sil'hooettes, as they are sometimes called, have performed for thousands of people at such venues as the Kennedy Center, The White House, John Paul Jones Arena, Baltimore Orioles home baseball games, and Boston Red Sox home baseball games.