late 15c., "a guide," from Anglo-French directour, French directeur, agent noun from Latin dirigere "set straight, arrange; give a particular direction to," from dis- "apart" (see dis-) + regere "to direct, to guide, keep straight" (from PIE root *reg- "move in a straight line").
Corporate sense of "one of a number of persons having authority to manage the affairs of a company" is from 1630s; theatrical sense of "the leader of a company of performers" is from 1911.
1640s, "capable of performance" (a sense now obsolete), also "of the branch of government that carries out the laws," from Latin executivus, from past participle stem of exequi "follow after; carry out, accomplish" (see execution). The sense of "concerned with or pertaining to the function of carrying into practical effect" is from 1670s. The noun meaning "person or persons invested with supreme executive power in a country" is from 1776, as a branch of government charged with the execution and enforcement of the laws. Meaning "high-ranking businessman, person holding an executive position in a business organization" is by 1902 in American English; hence the adjectival sense "stylish, luxurious, costly" (1970s). Executive privilege in reference to the U.S. president is attested by 1805, American English.
1630s, "of or befitting to a master or teacher or one qualified to speak with authority," from Medieval Latin magisterialis "of or pertaining to the office of magistrate, director, or teacher," from Late Latin magisterius "having authority of a magistrate," from magister "chief, director" (see master (n.)).
By 17c. often with a suggestion of "arrogant, imperious, domineering." Meaning "holding the office of a magistrate, proper to a magistrate" is from 1650s (see magistrate). Related: Magisterially.
mid-14c., administracioun, "act of giving or dispensing;" late 14c., "management (of a business, property, etc.), act of administering," from Latin administrationem (nominative administratio) "aid, help, cooperation; direction, management," noun of action from past-participle stem of administrare "to help, assist; manage, control, guide, superintend; rule, direct," from ad "to" (see ad-) + ministrare "to serve, attend, wait upon," from minister "inferior, servant, priest's assistant" (see minister (n.)).
It is attested by early 15c. as "management of a deceased person's estate under a commission from authority." The sense of "management of public affairs" is from 1680s; hence, "executive power in a government" (1731), though in Britain later government was used in this sense. The meaning "a U.S. president's period in office" is recorded by 1796 in the writings of George Washington.
The administration of government, in its largest sense, comprehends all the operations of the body politic, whether legislative, executive, or judiciary; but in its most usual, and perhaps in its most precise, signification, it is limited to executive details, and falls peculiarly within the province of the executive department. ["The Federalist," No. 72 (Hamilton)]