ver·nis·sage 
(vĕr′nĭ-säzh)
(vĕr′nĭ-säzh)n.
A private showing held before the opening of an art exhibition.
[French, varnishing, day before the official opening of an exhibition on which artists would varnish their paintings, vernissage, from vernis, varnish, from Old French; see VARNISH.]