Definition:  A threat against an information infrastructure can originate from any source.  It's a hazard that puts mission critical information at risk.

Included as dangers to maintaining security would be any condition, individual, Act of God or nature, crackers, cyber-criminals or cyber-terrorists that could result in the damage or destruction of an organization's information system. Hardware failures, power failures, software or software application failures as well as honest mistakes must also be considered risks and can cause significant problems that put the information assurance process at serious risk

threat, security threats