1 [noncount] a : the state of being protected or safe from harm ▪ We must insure our national security. —often used before another noun ▪ an electronic security system ▪ random security checks ▪ security measures b : things done to make people or places safe ▪ The college failed to provide adequate security on campus after dark. ▪ increased security at airports ▪ There was a lapse in security and the inmates escaped. c : the area in a place (such as an airport) where people are checked to make sure they are not carrying weapons or other illegal materials ▪ We have to go through security at the airport. d : the part of a company or other organization that provides protection for workers, equipment, etc. ▪ We called security when we found the door open.
2 [noncount] : the state of being closely watched or guarded ▪ The meeting was held under tight security. ▪ The prisoner was being kept under maximum security.
3 [noncount] : the state of being free from anxiety or worry : the state of being or feeling secure ▪ financial security ▪ She is concerned about job security. [=about the possibility of losing her job] ▪ 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.
4 [count] a : something given as proof of a promise to make a payment later ▪ security for a loan b : a document showing that someone owns or has invested in a company, organization, etc. ▪ government securities