Superlative form of bitchy: most bitchy.(adjective)
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Use "bitchiest" in a sentence
"June 02, 2009 at 8: 47 AM iPhone users are the bitchiest people I've ever seen."
"Hells yeah we loved her on Ugly Betty, and here it seems that she's pured the best, bitchiest parts of her Wilhelmina Slater into the form-fitting role of Renee, Lynette's married-to-money former college roomie."
"It's kind of anti-climactic and doesn't show any of her bitchiest moments, but I guess they're trying to make her look reasonably good since this is basically, like, a video ode."