Capital, a noun, refers to money or valuable assets, uppercase letters, and the primary city of a country or region (usually the seat of government and administration). Most situations call for capital, not Capitol (written with a capital c). Capitol refers to, as Thomas Jefferson wrote, in 1793, the “building in Washington, D.C., where U.S. Congress meets.” While Capitol comes from the Latin Capitolium (Jupiter’s temple on Capitoline Hill), capital comes from the Latin capitalis (of the head), a meaning it somewhat retains in its adjective form.