Unbreachable

Origin

- + breachable

Full definition of unbreachable

Adjective

1. Impossible to breach
• 2009, January 7, Zoe Williams, It's every cough mixture for itself in these times of ill, Cough medicine companies have to pretend that, illness be damned, ...
  we all love work and have a sworn, unbreachable fealty to our employer.