c. 1500, "a ceasing, an ending; a going away, act of leaving" (obsolete in this sense), from Old French departement "division, sharing out; divorce, parting" (12c.), from Late Latin departire "to divide" (transitive), from de- "from" (see de-) + partire "to part, divide," from pars (genitive partis) "a part, piece, a share, a division" (from PIE root *pere- (2) "to grant, allot").
French department came also to mean "group of people" (as well as "departure"), and from this by 1735 English had borrowed the sense of "separate division of a complex whole, separate business assigned to someone in a larger organization, distinct branch or group of activities" (science, business, manufacture, the military). The specific meaning "separate division of a government" is from 1769. As an administrative district in France, from 1792.
Department store "store that sells a variety of items, organized by department" is from 1878.
The "Department Store" is the outgrowth of the cheap counter business originated by Butler Brothers in Boston about ten years ago. The little "Five Cent Counter" then became a cornerstone from which the largest of all the world's branches of merchandising was to be reared. It was the "Cheap Counter" which proved to the progressive merchant his ability to sell all lines of wares under one roof. It was the Five Cent Counter "epidemic" of '77 and '78 which rushed like a mighty whirlwind from the Atlantic to the Pacific and all along its path transformed old time one line storekeepers into the wide-awake merchant princes of the present day. It was this same epidemic which made possible the world famed Department Stores of Houghton, of Boston; Macy, of New York; Wanamaker, of Philadelphia; and Lehman, of Chicago. [American Storekeeper, 1885]
c. 1300, "action of guarding or shielding from attack or injury; act of defending by fighting; a fortified place of refuge," from Old French defense, from Latin defensus, past participle of defendere "ward off, protect" (see defend). It also arrived (without the final -e) from Old French defens, from Latin defensum "thing protected or forbidden," neuter past participle of defendere.
Middle English defens was assimilated into defense, but not before it inspired the alternative spelling defence, via the same tendency that produced hence (hennis), pence (penies), dunce (Duns). Webster made the -se form standard in U.S., but British has preferred defence, and compare fence (n.).
Meaning "a speech or writing intended to repel or disprove a charge or accusation" is from late 14c., as is the sense of "method adopted by one against whom a lawsuit has been brought." Meaning "science of defense against attack" (in fencing, boxing, etc.) is from c. 1600. Used by 1935 as a euphemism for "national military resources," but the notion (non-euphemistic) was in Middle English: man of defense "warrior," ship of defense "warship." Defenses "natural weapons of an animal" is by 1889. Defense mechanism in psychology is from 1913.
computer programming language for use in business operations, 1960, U.S. Defense Department acronym, from "Common Business-Oriented Language."
1791, "pertaining to a (French) department, pertaining to a division of a country," from French départmental, from département (see department). Meaning "of departmental systems generally" from 1832. Related: Departmentally.
c. 1400, "serving to defend, proper for defense; of the nature of defense," from Old French defensif (14c., Modern French défensif) and directly from Medieval Latin defensivus, from defens-, past participle stem of Latin defendere (see defend). Of persons, "alert to reject criticism," from 1919. Related: Defensively; defensiveness.
As a noun, "that which defends or serves for defense," c. 1400, originally of medicines. Meaning "posture or attitude of defense" is from c. 1600.