vernissage

noun, plural ver·nis·sages [ver-nuh–sah-zhiz; French ver-nee-sazh] /ˌvɛr nəˈsɑ ʒɪz; French vɛr niˈsaʒ/.

1. Also called varnishing day. the day before the opening of an art exhibition traditionally reserved for the artist to varnish the paintings.
2. a reception at a gallery for an artist whose show is about to open to the public.

noun

1. a preview or the opening or first day of an exhibition of paintings
2. another term for varnishing day