Definition of "Security" :

noun: measures taken as a precaution against theft or espionage or sabotage etc.

"Military security has been stepped up since the recent uprising."

noun: an electrical device that sets off an alarm when someone tries to break in

noun: a guarantee that an obligation will be met

noun: freedom from anxiety or fear

"The watch dog gave her a feeling of security."

noun: a department responsible for the security of the institution's property and workers

"The head of security was a former policeman."

noun: defense against financial failure; financial independence

"His pension gave him security in his old age."

noun: property that your creditor can claim in case you default on your obligation

"Bankers are reluctant to lend without good security."

noun: a formal declaration that documents a fact of relevance to finance and investment; the holder has a right to receive interest or dividends

noun: the state of being free from danger or injury

"We support the armed services in the name of national security."