Learner's definition of SECURITY
1 a : the state of being protected or safe from harm — often used before another noun b : things done to make people or places safe
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 d : the part of a company or other organization that provides protection for workers, equipment, etc.
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.
2 [noncount] : the state of being closely watched or guarded 3 [noncount] : the state of being free from anxiety or worry : the state of being or feeling secure
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 a : something given as proof of a promise to make a payment later b : a document showing that someone owns or has invested in a company, organization, etc.