The noun security has 9 senses (first 9 from tagged texts)
1. (304) security -- (the state of being free from danger or injury; "we support the armed services in the name of national security")
2. (222) security, certificate -- (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")
3. (162) security, security department -- (a department responsible for the security of the institution's property and workers; "the head of security was a former policeman")
4. (110) security, security measures -- (measures taken as a precaution against theft or espionage or sabotage etc.; "military security has been stepped up since the recent uprising")
5. (77) security, protection -- (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")
6. (29) security -- (freedom from anxiety or fear; "the watch dog gave her a feeling of security")
7. (19) security system, security measure, security -- (an electrical device that sets off an alarm when someone tries to break in)
8. (10) security, surety -- (property that your creditor can claim in case you default on your obligation; "bankers are reluctant to lend without good security")
9. (3) security, surety -- (a guarantee that an obligation will be met)