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11.
something that is fantastic (usually referring towards the buttox area).
That girl is lookin' asstastic today!
by hallelujiah March 15, 2010
 
1.
1. Extremely bad; abominable
2. Extremely evil or cruel
1. The party-goers were completely out of control and left behind an asstastic mess.

2. "That asstastic whore just dumped me for my brother!"
by Trendon August 23, 2005
 
2.
Adjective.
Definition 1: A complimentary statement of one's posterior.
Synonym: Bootylicious

Definition 2: A durogatory comment regarding someone who excels at being a fantastic asshole.
Synonym: Colossus Assholus
Example 1: "Gee, these pants make my rear end look asstastic!!"

Example 2: "My ex was asstastic, he left me destitute."
by Maven April 15, 2004
 
3.
(adj.)having a great ass
Man that girl is asstastic!
by The Gizza February 07, 2003
 
4.
The opposite of fantastic.
"You really did an asstastic job there, Billy"
by Anonymous September 30, 2003
 
5.
1. When talking about a person, it's a good term, meaning they are attractive in the ass department.

2. When used in a situation, this means you are not satisfied with the outcome.
1. Damn, Jennifer Aniston is asstastic!
2. I'm going to the dentist today, this shit's asstastic.
by i look like hell August 17, 2009
 
6.
Asstastic is a combination of "Ass" and "Fantastic." Was created as a satire of all words that ironically mean "excellent," such as cool, wicked, tight, gnarly and sick.
"I just saw Sin City! It was Asstastic!"
by Heather M. May 06, 2005
 
7.
When a girl named steely enjoy many a nights of anal butt pleasures
Damn that gurl steely is ass tastic!
by damb112 December 08, 2008