Biggest country in the world search

http://geography.about.com/od/countryinformation/a/bigcountries.htm:

Biggest: Russia

http://en.m.wikipedia.org/wiki/List_of_countries_and_dependencies_by_area:

Biggest: Russia

http://www.nationsonline.org/oneworld/countries_by_area.htm:

Biggest: Russia

So after my research, the answer is clear: Russia!