Definition of “security”

noun

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)
   1. a certificate of creditorship or property carrying the right to receive interest or dividend, such as shares or bonds
   2. 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