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1.
Experting is someone widely recognized as a reliable source of technique or skill whose faculty for judging or deciding rightly, justly, or wisely is accorded authority and status by their peers or the public in a specific well-distinguished domain.
Experting is amazing.
by Justoldme July 19, 2010
 
2.
Verb-

to tell someone something with unwavering authority & confidence, when in fact, you have no real knowledge of the subject -usually done by a blowhard.
Yeah, he's experting on that guy, he has no idea what he's talking about.
by hammertime-tm September 10, 2008