early 14c., "one who holds an official post, one entrusted with a responsibility or share of the management of some undertaking" (originally a high office), from Old French oficier "officer, official" (early 14c., Modern French officier), from Medieval Latin officiarius "an officer," from Latin officium "a service, a duty" (see office).
In Middle English also "a servant, a retainer of a great household; an official at court" (late 14c.). From late 14c. as "a military retainer," but the modern military sense of "one who holds a commission in the army or navy" is from 1560s. Applied to petty officials of justice from 16c.; U.S. use in reference to policemen is from 1880s.
The phrase officer and a gentleman in reference to one having the qualities of both is by 1762 and was standard language in British court-martial indictments ("behaviour infamous and scandalous such as is unbecoming the character of an officer and a gentleman").
The words 'officer and gentleman,' though in general to be understood as one single and indivisible term, appear not to be so used here. The misbehaviour, entailing on it the penalty declared by this article, must be such, as I understand it, as to implicate, in the first place, the officer; that is, it must arise in some sort out of his office; and affect incidentally only, the character of the gentleman. It must be such a misconduct, as must necessarily dissever what should ever be indivisible, the consideration of the officer from the gentleman. It must be of that decisively low, humiliating, and debasing kind, as to lay prostrate the honour of the gentleman, in the degradation of the officer. [Capt. Hough and George Long, "The Practice of Courts-Martial," London, 1825]
c. 1300, "highest in rank or power; most important or prominent; supreme, best, placed above the rest," from Old French chief "chief, principal, first" (10c., Modern French chef), from Vulgar Latin *capum (also source of Spanish and Portuguese cabo, Italian capo, Provençal cap), from Latin caput "head," also "leader, guide, chief person; summit; capital city" (from PIE root *kaput- "head").
late 14c., peti, "small, little, minor," from a phonemic spelling of Old French petit "small" (see petit). From late 12c. in surnames. In English, not originally disparaging (as still in petty cash "small sums of money received or paid," 1834; petty officer "minor or inferior military officer," 1570s).
Meaning "of small or minor importance, not serious" is recorded from 1520s; that of "small-minded" is from 1580s. Related: Pettily; pettiness.
c. 1300, "head, leader, captain; the principal or most important part of anything;" from Old French chief "leader, ruler, head" of something, "capital city" (10c., Modern French chef), from Vulgar Latin *capum, from Latin caput "head," also "leader, chief person; summit; capital city" (from PIE root *kaput- "head"). Meaning "head of a clan" is from 1570s; later extended to headmen of Native American tribes (by 1713; William Penn, 1680s, called them kings). Commander-in-chief is attested from 1660s.
c. 1200, "chief household officer;" c. 1300, "justice of the peace," from Old French conestable (12c., Modern French connétable), "steward, governor," principal officer of the Frankish king's household, from Medieval Latin conestabulus, from Late Latin comes stabuli, literally "count of the stable" (established by Theodosian Code, c. 438 C.E.), hence, "chief groom."
For first element, see count (n.1). Second element is from Latin stabulum "stable, standing place" (see stable (n.)). Probably the whole is a loan-translation of a Germanic word. Compare marshal (n.).
Meaning "an officer chosen to serve minor legal process" is from c. 1600, transferred to "police officer" by 1836. French reborrowed constable 19c. as "English police."
1947, American English, "officer in charge," from Japanese hancho "group leader," from han "corps, squad" + cho "head, chief." Picked up by U.S. servicemen in Japan and Korea, 1947-1953.
military rank above captain and below lieutenant colonel, 1640s, from French major, short for sergent-major, originally a higher rank than at present, from Medieval Latin major "chief officer, magnate, superior person," from Latin maior "an elder, adult," noun use of the adjective (see major (adj.)).
His chief duties consist in superintending the exercises of his regiment or battalion, and in putting in execution the commands of his superior officer. His ordinary position in the line is behind the left wing. [Century Dictionary, 1897]
The musical sense is attested by 1797.
"petty officer who cites persons to appear in court," secular or ecclesiastical, early 14c. (mid-13c. as a surname), from Anglo-French sumenour, Old French somoneor, from Medieval Latin summonitorem, from past participle stem of summonere (see summon). Contracted form sumner is from mid-14c.