Same as bitch but is the epitome of the word. A contestible female who is self absorbed, materialistic, and often conniving.
Person 1: I won't even deal with (lisa), she'll screw you in a second, and won't think twice.
Person 2: Sounds pretty bad.
Person 1: Oh, yeah. She's the megabitch.
A female of super-sized, intolerable, and uncalled for bitchiness with an extra side of "Oh no she didn't..."
Talking amongst the chattering crowd...
Girl 1: I totally understand it now Krystyna, thanks!
Girl 2: No problem babe. Happy I cleared that up for y-
Megabitch: (Snaps to Girls) -Uh HELLO?! Excuse me? Do you have a question? Well do you? Oh well, shut your face because nobody cares.
Girl 1: Whoa! Somebody woke up on the wrong side of the bed this morning with a stick up their ass!
Girl 2: Yeah, that cunt is a total megabitch.