insecurity

Insecurity is the nagging doubt that you are not good enough. It usually arrives quietly and then stays.

The personal sense is the commoner one: hiding an insecurity, an insecurity about his height, and often the plural, since everyone has their insecurities. A second sense is entirely practical and about safety rather than feelings, which is where job insecurity, food insecurity and housing insecurity come from. Both go back to secure, and both describe ground that will not hold.