Also defined as "universal artwork" in entry at ArtLex Art Dictionary
A Gesamtkunstwerk (translated as total work of art, ideal work of art, universal artwork, synthesis of the arts, comprehensive artwork, all-embracing art form, or total artwork) is a work of art that makes use of all or many art forms or strives to do so. The term is a German word which has come to be accepted in English as a term in aesthetics.
The term was first used by the German writer and philosopher K. F. E. Trahndorff in an essay in 1827. The German opera composer Richard Wagner used the term in an 1849 essay. It is unclear whether Wagner knew of Trahndorff's essay. The word has become particularly associated with Wagner's aesthetic ideals.
I've deliberately not omitted the citations numbers.