1 [U] the state of feeling safe and being free from worry; protection against the difficulties of life 安全感；安稳；保障: Children need the security of a stable home environment. 孩子需要安稳的家庭环境。financial/job security 经济╱工作保障 [OPP] insecurity 反义词为insecurity

2 [U] things that you do to protect sb/sth from attack, danger, thieves, etc 安全措施；保安措施: Security was tightened at the airport before the president arrived. 总统到达前，机场的保安措施加强了。The robbers were caught on the bank's security cameras. 这几个窃贼给银行的保安摄像机录了下来。

3 [U] the section of a large company or organization that deals with the protection of buildings, equipment and staff （公司或机构的）保安部门: If you see a suspicious bag, contact airport security immediately. 如果看到一个可疑的袋子，请马上与机场的保安部门联系。

4 [C,U] something of value that you use when you borrow money. If you cannot pay the money back then you lose the thing you gave as security 抵押品