causing much harm, injury, or destruction (usually by insidious undermining); deadly.
Main Example
Recent instances of nudity during prime time television have Congress fuming. Pointing to the Janet Jackson incident and a CBS ad in which a woman wearing only a T-shirt exposes her naked buttocks to an eight-year-old boy as she reaches for a high kitchen cabinet, lawmakers from both parties have demanded that the FCC urgently arrest the rising tide of indecency on TV because of its pernicious effect on our children.
Workplace Examples
Yes, we must curb Internet misuse, but not by encouraging employees to report against one another. That sort of thing can be pernicious because it destroys workplace harmony.
Ken's report clearly shows that we wouldn't be in this crisis, had we paid attention to what the market was telling us all along. Because we so perniciously ignored sales trends and warnings from our distributors, we are now in a huge mess.
Other Examples
the widely respected Arthur Levitt, former SEC chair, repeatedly warning Americans against the pernicious myth that day trading is glamorous, macho, and easy money
the increasing and pernicious stranglehold of special interest money on politics as the cost of campaigning rises exponentially every election cycle
pernicious computer viruses such as the Sobig which affected several hundred thousand computers and cost businesses billions of dollars
the perniciousness of the market reforms carried out in Russia during the 1990s: tens of millions of Russians are suffering extreme poverty and are far worse off today than under Soviet rule