An overcompensating female executive who takes every opportunity to establish and assert dominance by being unnecessarily bitchy and bossy towards colleagues and underlings.
Not every female executive is an Execubitch. But if you do have the opportunity to witness a transformation from female colleague to Execubitch, it is usually followed by a short haircut and an inexplicable urge to fill her closet with pant suits.
I don't know what happened to Sally, she used to pretty cool. But once she got promoted to VP, she just goes around trying to throw everyone under the bus at staff meetings. She's turned into such an Execubitch.