Old English bisignes (Northumbrian) "care, anxiety, occupation," from bisig "careful, anxious, busy, occupied, diligent" (see busy (adj.)) + -ness. The original sense is obsolete, as is the Middle English sense of "state of being much occupied or engaged" (mid-14c.), the latter replaced by busyness. Johnson's dictionary also has busiless "At leisure; without business; unemployed." Modern two-syllable pronunciation is 17c.
Sense of "a person's work, occupation, that which one does for a livelihood" is first recorded late 14c. (in late Old English bisig (adj.) appears as a noun with the sense "occupation, state of employment"). Sense of "that which is undertaken as a duty" is from late 14c. Meaning "what one is about at the moment" is from 1590s. Sense of "trade, commercial engagements, mercantile pursuits collectively" is first attested 1727, on the notion of "matters which occupy one's time and attention." In 17c. business also could mean "sexual intercourse."
Business card first attested 1840; business letter from 1766. Business end "the practical or effective part" (of something) is American English, by 1874. Phrase business as usual attested from 1865. To mean business "be intent on serious action" is from 1856. To mind (one's) own business "attend to one's affairs and not meddle with those of others" is from 1620s.
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.
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)]
"office or official position of a secretary" in the administrative and executive sense, 1811, from French secrétariat, from Medieval Latin secretariatus "the office of a secretary," from secretarius "clerk, notary, confidential officer, confidant" (see secretary). Meaning "division of the Central Committee of the USSR" (with capital S-) is from 1926, from Russian sekretariat.
"the executive branch of the public service," as distinguished from the military, naval, legislative, or judicial, 1765, originally in reference to non-military staff of the East India Company, from civil in the sense "not military." Civil servant is from 1792.