Art Deco French

what does ART DECO NOUVEAU? mean?
i presume nouveau is french for something, i am looking at jewelery online and a lot of pieces say this.
Art Deco and Art Nouveau are two different styles. Art Nouveau, which means New Art was popular around the turn of the century (20th century). It was notable for its flowing, organic lines. (See Alfonse Mucha posters.) Art Deco rolled around about 1920 or so, and characterized more by geometric shapes. Presently it seems that Art Deco is more popular, especially in jewelry, whereas Art Nouveau experienced a rebirth of popularity in the 70s. Both though are highly valued by collectors.