The screen came up to light again, showing a devastated section of the city grid. No, not decimated. Had that part of the city been decimated, one out of every ten buildings would be destroyed. That's what means. Personally, I think some early-years, respected television personality got and confused at some point, and no one wanted to point it out to him, so everyone started using them interchangeably. But dammit, words mean what they mean, even if everyone thinks they ought to mean something else.