Insanely ugly woman, having the characteristics of all or any of the animals involved in the word, be it
Hippo, Crocodile, Dog, or
Pig.
Someone who qualifies as a real hippocrocadogapig is not someone you would want to have sex with in a hurry. A real ten pinter.
Credit for this to Gail, it's been a useful word all too often since I learnt it.