1818 as a purely geographical term, "relating to or of the nature of a continent," from continent (n.) + -al (1). In reference to the European mainland (as opposed to Great Britain), recorded from 1760. Continental breakfast (the kind eaten on the continent as opposed to the kind eaten in Britain) is attested by 1855.
As "pertaining to the government and affairs of the 13 revolutionary British American colonies," from 1774; the Continental Congress is attested from 1775.
Continental divide "line across a continent such that the drainage on one side feeds into one ocean or sea and that on the other feeds into a different body of water," was in use by 1865; continental slope "slope between the outer edge of the continental shelf and the ocean floor" is from 1849. Continental shelf "area of shallow sea around a continent, geologically part of the continent" is first attested 1888.
Continental drift "gradual movement of the continents across the earth's surface through geological time" (1925) is a translation of German Kontinentalverschiebung, proposed 1912 by German scientist Alfred Wegener (1880-1930); the theory was not widely accepted until after c. 1950.
1777, "soldier of the regular army of the rebelling British American colonies," from continental (adj.) in its specific sense. In the general sense "native or inhabitant of a continent" from 1828.
Also used of the paper money issued by the rebelling colonies, which, through its devaluation, led to the expression not worth a continental (which seems to be no earlier than 1851), sometimes not worth a continental dime.