noun, plural securities.
freedom from danger, risk, etc.; safety.
freedom from care, anxiety, or doubt; well-founded confidence.
something that secures or makes safe; protection; defense.
freedom from financial cares or from want: The insurance policy gave the family security.
precautions taken to guard against crime, attack, sabotage, espionage, etc.: The senator claimed security was lax and potential enemies know our plans.
a department or organization responsible for protection or safety: He called security when he spotted the intruder.
protection or precautions taken against escape; custody: The dangerous criminal was placed under maximum security.
an assurance; guarantee.
something given or deposited as surety for the fulfillment of a promise or an obligation, the payment of a debt, etc.
one who becomes surety for another.
an evidence of debt or of property, as a bond or a certificate of stock.
Usually, securities. stocks and bonds.
Archaic. overconfidence; cockiness.
of, pertaining to, or serving as security: The company has instituted stricter security measures.

1400–50; late Middle English securytye, securite(e) < Latin sēcūritās. See secure, -ity

nonsecurity, noun, plural nonsecurities.
oversecurity, noun
self-security, noun
subsecurity, noun, plural subsecurities.

2. assurance, certainty, positiveness. 3. safeguard, safety. Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
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World English Dictionary
security (sɪˈkjʊərɪtɪ)
n , pl -ties
1.  the state of being secure
2.  assured freedom from poverty or want: he needs the security of a permanent job
3.  a person or thing that secures, guarantees, etc
4.  precautions taken to ensure against theft, espionage, etc: the security in the government offices was not very good
5.  (often plural)
 a.  a certificate of creditorship or property carrying the right to receive interest or dividend, such as shares or bonds
 b.  the financial asset represented by such a certificate
6.  the specific asset that a creditor can claim title to in the event of default on an obligation
7.  something given or pledged to secure the fulfilment of a promise or obligation
8.  a person who undertakes to fulfil another person's obligation
9.  the protection of data to ensure that only authorized personnel have access to computer files
10.  archaic carelessness or overconfidence

Collins English Dictionary - Complete & Unabridged 10th Edition
2009 © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009
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Word Origin & History

early 15c., from L. securitas, from securus (see secure); phrase security blanket in figurative sense is attested from 1971, in reference to the crib blanket carried by the character Linus in the "Peanuts" comic strip (1956).
Online Etymology Dictionary, © 2010 Douglas Harper
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Computing Dictionary

security definition

Protection against unauthorized access to, or alteration of, information and system resources including CPUs, storage devices and programs.
Security includes:
* confidentiality - preventing unauthorized access; integrity - preventing or detecting unauthorized modification of information.
* authentication - determining whether a user is who they claim to be.
* access control - ensuring that users can access the resources, and only the resources, that they are authorised to.
* nonrepudiation - proof that a message came from a certain source.
* availability - ensuring that a system is operational and accessible to authorised users despite hardware or software failures or attack.
* privacy - allowing people to know and control how information is collected about them and how it is used.
Security can also be considered in the following terms:
* physical security - who can touch the system to operate or modify it, protection against the physical environment - heat, earthquake, etc.
* operational/procedural security - who is authorised to do or responsible for doing what and when, who can authorise others to do what and who has to report what to who.
* personnel security - hiring employees, background screening, training, security briefings, monitoring and handling departures.
* System security - User access and authentication controls, assignment of privilege, maintaining file and filesystem integrity, backup, monitoring processes, log-keeping, and auditing.
* network security - protecting network and telecommunications equipment, protecting network servers and transmissions, combatting eavesdropping, controlling access from untrusted networks, firewalls, and intrusion detection.
Encryption is one important technique used to improve data security.
OWASP is the free and open application security community.
The Free On-line Dictionary of Computing, © Denis Howe 2010
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American Heritage
Idioms & Phrases


In addition to the idiom beginning with security, also see lull into (false sense of security).

The American Heritage® Dictionary of Idioms by Christine Ammer.
Copyright © 1997. Published by Houghton Mifflin.
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Example sentences
Unlike a bond, this security has no redemption value.
Through this, homogeneity was maintained through the centuries, with geography providing safety and security.
Please consider what this will mean to our future, to science, even to our
We have taken all reasonable steps to implement multiple security layers in the
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