secret

Definitions

General English

  • noun a thing which is not known or which is kept hidden

Banking

  • noun something which is kept hidden or which is not known about by many people

Information & Library Science

  • noun a piece of information that is known only to a few people and is intentionally withheld from general knowledge

Military

  • adjective high level of security classification for documents and information

Origin & History of “secret”

Etymologically, something that is secret is ‘separated’ from others, hence put out of the way, hidden. The word comes via Old French secret from Latin sēcrētus, an adjectival use of the past participle of sēcernere ‘separate’. this was a compound verb formed from the prefix - ‘apart’ and cernere ‘separate’ (source also of English certain, discern, excrement, etc). From the 16th to the 18th centuries, secret was used as a verb, meaning ‘hide’, but it was then altered to secrete, on the model of Latin sēcrētus. (The other verb secrete, ‘produce fluids or other substances’ (18th c.), is a back-formation from secretion (17th c.), which goes back to Latin sēcrētiō ‘separation’, a derivative of sēcernere.) A secretary is etymologically a ‘secret’ or confidential helper.
http://www.dictionarycentral.com/definition/secret.html