1530s, "without care or fear, dreading no evil" (a sense now archaic), from Latin securus, of persons, "free from care, quiet, easy," also in a bad sense, "careless, reckless;" of things, "tranquil; free from danger, safe," from *se cura, from se "free from" (see se-) + cura "care" (see cure (n.)).
In early use it often implied "over-confident, too sure." In English, in reference to places, "free from danger, unexposed," by c. 1600. The mechanical meaning "firmly fixed" (of material things) is by 1841, extended from the mental meaning "affording grounds for confidence" (1580s) hence "of such stability, strength, etc. to preclude risk." Of telephones or telephone lines, "not wiretapped," by 1961.
The earlier word, or form of the word, was Middle English siker, from Old English sicor, an earlier borrowing of the same Latin word, and sure (adj.) is a doublet, altered in its passage through Old French. Related: Securely.
c. 1600, "to make safe, guard from danger," from secure (adj.). Meaning "ensure, make certain, guarantee" is from 1650s; that of "seize and hold" (in reference to persons) is from 1640s; that of "make fast or firm" (of things) is from 1650s. The sense of "get possession of, make oneself master of" is from 1743. Related: Secured; securing.
late 14c., "reassure, give confidence to; make secure or safe, protect; bind by a pledge, give a promise or pledge (to do something)," from Old French asseurer "to reassure, calm, protect, to render sure" (12c., Modern French assurer), from Vulgar Latin *assecurar, from assimilated form of Latin ad "to" (see ad-) + securus "safe, secure" (see secure (adj.)). Related: Assured; assuring.
c. 1300, "a guarantee, promise, pledge, an assurance," from Old French seurté "a promise, pledge, guarantee; assurance, confidence" (12c., Modern French sûreté), from Latin securitatem (nominative securitas) "freedom from care or danger, safety, security," from securus (see secure (adj.)). From late 14c. as "security, safety, stability; state of peace," also "certainty, certitude; confidence." Meaning "one who makes himself responsible for another" is from early 15c. Until 1966, the French national criminal police department was the Sûreté nationale.
early 13c., "safe against attack, secure," later "firm, reliable" (c. 1300); "mentally certain, confident" (mid-14c.); "firm, strong, resolute" (c. 1400), from Old French seur, sur "safe, secure; undoubted, dependable, trustworthy" (12c.), from Latin securus "free from care, untroubled, heedless, safe" (see secure (adj.)).
The pronunciation development is that of sugar (n.). The colloquial pronunciation "sho" is attested by 1871 in representations of U.S. Black speech (fo sho); compare mo.
As an affirmative meaning "yes, certainly" it dates from 1803, from Middle English meanings "firmly established; having no doubt," and phrases such as to be sure (1650s), sure enough (1540s), and for sure (1580s).
The use as an adverb meaning "assuredly" goes back to early 14c. Sure-footed is from 1630s, literal and figurative; sure thing dates from 1836. In 16c.-17c., Suresby was an appellation for a person to be depended upon (see rudesby).
early 15c., securite, "state or condition of being safe from danger or harm;" mid-15c., "freedom from care or anxiety" (a sense now archaic), from Old French securite and directly from Latin securitas "freedom from care," from securus "free from care" (see secure (adj.)).
This form replaced the earlier sikerte (early 15c.), which represents an earlier borrowing of the Latin word; earlier in English in the sense of "security" was sikerhede (early 13c.); sikernesse (c. 1200). Sir Thomas Browne uses securement; Francis Bacon and Mrs. Browning have secureness. Surety is a doublet, via French.
The meaning "something which secures, that which makes safe" is from 1580s. The specific legal sense of "something pledged as a guarantee of fulfillment of an obligation" is from mid-15c. (originally a guarantee of good behavior).
The meaning "safety of a state, person, etc." is by 1941. By 1965 Security, with the capital, was generic or shorthand for "security officials; a state's security department or ministry."
The legal sense of "property in bonds" is from mid-15c.; that of "document held by a creditor as evidence of debt or property and proof of right to payment" is from 1680s. Security-check (n.) is by 1945. Phrase security blanket in figurative sense is attested by 1966, in reference to the crib blanket carried by the character Linus in the popular "Peanuts" newspaper comic strip (the blanket, and the strip, from 1956).
[fee to secure services] mid-15c., "act of keeping for oneself, an authorized retention (of dues, etc.)," an agent noun from retain (v.), or perhaps from or influenced by French retenir, infinitive used as a noun. Meaning "a retaining fee, fee paid to an attorney or barrister to secure his services" is from 1818. The general sense of "sum paid to secure special services" is from 1859.