1.Definition: lacking in security or safety

"His fortune was increasingly insecure", "An insecure future"

Related Adjective(s):unsafe

2.Definition: lacking self-confidence or assurance

"An insecure person lacking mental stability"

3.Definition: not firm or firmly fixed; likely to fail or give way

"The hinge is insecure"

4.Definition: not safe from attack

Related Adjective(s):unsafe