rez-de-chaussée

from The Century Dictionary.

• noun The ground floor of a building; the floor in which are the principal entrances, even if it is two or three feet above the level of the site.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Arch.) The ground story of a building, either on a level with the street or raised slightly above it; -- said esp. of buildings on the continent of Europe.