Something that can kill somebody if it fails is LifeCritical.  Electrical appliances, boats, medical equipment, are all LifeCritical.  Software is rarely LifeCritical; exceptions include life-support systems, power plant software, fly-by-wire systems, and patient monitoring software.

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Although, I guess it's not part of the official definition of an Engineer, there's a definite sense that Engineers do LifeCritical stuff.  And yet if most software is MoneyCritical rather than LifeCritical... 

As an example, I remember the LeadEngineer for the PrinceEdwardIsland bridge talking about how few people died on the project.  Note that "few" is greater than zero. --JasonYip