Is it ensure, insure, or assure?
mid-15c., "first in time;" late 15c. as "first in rank," from Middle French premier "first, chief," from Latin primarius "of the first rank, chief" (see primary (adj.)).
1711 in the political sense, a shortening of premier minister (1680s); see premier (adj.). In U.S. usage, premier formerly was applied occasionally to the Secretary of State (1855-c.1900).