sergeantyoudaoicibaDictYouDict[sergeant 词源字典]
sergeant: [12] A sergeant is etymologically simply a ‘servant’ – and indeed that is what the word originally meant in English. It comes via Old French sergent from Latin servient-, the present participial stem of servīre ‘serve’. It was subsequently incorporated into the terminology of the feudal system, roughly equivalent in application to esquire, and it was also used for various legal officers, but it does not seem to have become a specific military rank until the mid 16th century. ‘Sergeant’ then was a comparatively exalted position, but by the end of the century we see it settling into its modern niche as a senior noncommissioned officer.
=> servant, serve[sergeant etymology, sergeant origin, 英语词源]
sergeant (n.)youdaoicibaDictYouDict
c. 1200, "servant," from Old French sergent, serjant "(domestic) servant, valet; court official; soldier," from Medieval Latin servientum (nominative serviens) "servant, vassal, soldier" (in Late Latin "public official"), from Latin servientem "serving," present participle of servire "to serve" (see serve (v.)); cognate with Spanish sirviente, Italian servente; a twin of servant, and 16c. writers sometimes use the two words interchangeably.

Specific sense of "military servant" is attested from late 13c.; that of "officer whose duty is to enforce judgments of a tribunal or legislative body" is from c. 1300 (sergeant at arms is attested from late 14c.). Meaning "non-commissioned military officer" first recorded 1540s. Originally a much more important rank than presently. As a police rank, in Great Britain from 1839.

Middle English alternative spelling serjeant (from Old French) was retained in Britain in special use as title of a superior order of barristers (c. 1300, from legal Latin serviens ad legem, "one who serves (the king) in matters of law"), from which Common Law judges were chosen; also used of certain other officers of the royal household. sergeant-major is from 1570s. The sergeant-fish (1871) so-called for lateral markings resembling a sergeant's stripes. Related: Sergeancy.