security

noun

se·​cu·​ri·​ty si-ˈkyu̇r-ə-tē 

-ˈkyər-

plural securities

1

: the quality or state of being secure: such as

a

: freedom from danger : safety

b

: freedom from fear or anxiety

c

: freedom from the prospect of being laid off

job security

2

a

: something given, deposited, or pledged to make certain the fulfillment of an obligation

b

: surety

3

: an instrument of investment in the form of a document (such as a stock certificate or bond) providing evidence of its ownership

4

a

: something that secures : protection

b(1)

: measures taken to guard against espionage or sabotage, crime, attack, or escape

(2)

: an organization or department whose task is security

5

: the state of being able to reliably afford or access what is needed to meet one's basic needs

According to a media release, the investments are going to community partners helping parents, families and individuals in need … and assisting with housing security …

—Health & Beauty Close-Up

Synonyms

• defense
• protection
• safeguard
• ammunition
• shield
• wall

Examples of security in a Sentence

We must insure our national security.

The college failed to provide adequate security on campus after dark.

There was a lapse in security and the inmates escaped.

We have to go through security at the airport.

We called security when we found the door open.

The meeting was held under tight security.

The prisoner was being kept under maximum security.

I like the security of knowing there will be someone there to help me when I need help.

Growing up in a close family gave her a sense of security.

Recent Examples on the Web

The Madoff case stems from a 2009 lawsuit by Herald Fund SPC against HSBC's Luxembourg arm, seeking the return of securities and cash allegedly lost in the fraud. —Lee Ying Shan, CNBC, 28 Oct. 2025

On Tuesday, Sanae Takaichi met face-to-face with a man who has rattled leaders around the world, including her Japanese predecessors, on both security and economic fronts. —Miranda Jeyaretnam, Time, 28 Oct. 2025

Their talks are expected to cover tariffs, regional security and Japan’s defense spending, all points of tension in recent months. —Hanako Montgomery, CNN Money, 27 Oct. 2025

According to food-security experts, extreme malnutrition in Gaza, already high, skyrocketed after GHF took over; according to Netanyahu, the foundation failed to prevent looting by Hamas. —Hana Kiros, The Atlantic, 27 Oct. 2025

Word History

First Known Use

15th century, in the meaning defined at sense 1

Phrases Containing security

• collective security
• false sense of security
• high-security
• maximum security prison
• minimum security prison
• security blanket
• security camera
• security check
• security clearance
• security deposit
• security guard
• security interest
• security police
• security risk
• social security

Rhymes for security

• impurity
• maturity
• obscurity
• biosecurity
• cybersecurity
• immaturity
• insecurity
• prematurity
• purity
• surety

Kids Definition

security

noun

se·​cu·​ri·​ty si-ˈkyu̇r-ət-ē 

plural securities

1

: the state of being secure : safety

2

: something given as a pledge

security for a loan

3

: a document (as a stock certificate or bond) providing evidence of ownership

government securities

4

: something that secures : protection

especially : measures taken to guard against spying or destructive actions

concerns over national security

Medical Definition

security

noun

se·​cu·​ri·​ty si-ˈkyu̇r-ət-ē 

plural securities

: freedom from fear or anxiety

need for security dates back into infancy

—K. C. Garrison

Legal Definition

security

noun

se·​cur·​i·​ty si-ˈkyu̇r-ə-tē 

plural securities

1

a

: something (as a mortgage or collateral) that is provided to make certain the fulfillment of an obligation

used his property as security for a loan

b

: surety see also security for costs

2

: evidence of indebtedness, ownership, or the right to ownership

specifically : evidence of investment in a common enterprise (as a corporation or partnership) made with the expectation of deriving a profit solely from the efforts of others who acquire control over the funds invested

a security involves some form of investment contract

see also due diligence

— asset-backed security

: a security (as a bond) that represents ownership in or is secured by a pool of assets (as loans or receivables) that have been securitized

— bearer security

: a security (as a bearer bond) that is not registered and is payable to anyone in possession of it

— certificated security \ sər-​ˈti-​fə-​ˌkā-​təd-​ \

: a security that belongs to or is divisible into a class or series of shares, participations, interests, or obligations, is a commonly recognized medium of investment, and is represented on an instrument payable to the bearer or a specified person or on an instrument registered on books by or on behalf of the issuer

— convertible security

: a security (as a share of preferred stock) that the owner has the right to convert into a share or obligation of another class or series (as common stock)

— debt security

: a security (as a bond) serving as evidence of the indebtedness of the issuer (as a government or corporation) to the owner

— equity security

: a security (as a share of stock) serving as evidence of an ownership interest in the issuer

also : one convertible to or serving as evidence of a right to purchase, sell, or subscribe to such a security

— exempted security

: a security (as a government bond) exempt from particular requirements of the Securities and Exchange Commission (as those relating to registration on a security exchange)

— fixed-income security

: a security (as a bond) that provides a fixed rate of return on an investment (as because of a fixed interest rate or dividend)

— government security

: a security (as a Treasury bill) that is issued by a government, a government agency, or a corporation in which a government has a direct or indirect interest

— hybrid security

: a security with characteristics of both an equity security and a debt security

— mortgage-backed security

: a security that represents ownership in or is secured by a pool of mortgage obligations

specifically : a pass-through security based on mortgage obligations

— pass-through security

: a security representing an ownership interest in a pool of debt obligations from which payments of interest and principal pass from the debtor through an intermediary (as a bank) to the investor

especially : one based on a pool of mortgage obligations guaranteed by a federal government agency compare collateralized mortgage obligation, remic

— registered security

: a security (as a registered bond) whose owner is registered on the books of the issuer

: a security that is to be offered for sale and for which a registration statement has been submitted

— restricted security

: a security accompanied by restrictions on its free transfer or registration of transfer

— shelf security

: a corporate security held for deferred issue in a shelf registration

— Treasury security

: a security issued by a government treasury : treasury sense 3

— uncertificated security \ ˌən-​sər-​ˈti-​fə-​ˌkā-​təd-​ \

: a security that belongs to or is divisible into a class or series of shares, participations, interests, or obligations, that is a commonly recognized medium of investment, that is not represented by an instrument, and the transfer of which is registered on books by or on behalf of the issuer

— unregistered security

: a security for which a registration statement has not been filed

— when-issued security

: a security traded on a conditional basis prior to its issue

3

a

: measures taken to guard against espionage or sabotage, crime, attack, or escape

b

: an organization or department whose task is security