the state of being free from danger or injury
"we support the armed services in the name of national security"
defense against financial failure; financial independence
"his pension gave him security in his old age"
"insurance provided protection against loss of wages due to illness"
a formal declaration that documents a fact of relevance to finance and investment; the holder has a right to receive interest or dividends
"he held several valuable securities"
a department responsible for the security of the institution's property and workers
"the head of security was a former policeman"
an electrical device that sets off an alarm when someone tries to break in
"The new security on our front door went off last night because a cat knocked over the motion sensor."
measures taken as a precaution against theft or espionage or sabotage etc.
"military security has been stepped up since the recent uprising"
The condition of not being threatened, especially physically, psychologically, emotionally, or financially.
"After finally paying off his student loans and finding stable housing, Mark felt a profound sense of security he hadn't experienced in years."
In plain English: Security is the feeling of being safe and protected from harm.
"The hotel offers free security for all guests staying in the city center."
Usage: Use "security" to describe the state of safety from physical harm or financial loss, often appearing in phrases like "national security" or "feelings of insecurity." Avoid confusing it with the countable term "securities," which refers specifically to tradable assets like stocks and bonds.
The word security comes from the Latin sēcūrus, meaning "safe" or "secure," which was formed by combining sē- ("without") and cūra ("care"). It entered English via Middle French, carrying the original sense of being free from worry.