Rad and fantastic combined making a force to be rekoned with. If you are radtastic you are the best.
by sctso April 28, 2003
by AlanJohn January 21, 2008
by 1337solidsnake117 May 3, 2007
by Andy-Fuckin-V!!!! February 25, 2012
(adj) Something so great, or tremendous, and unbelievable that it supersedes all other synonyms of both good and extraordinary.
Although she was nothing more than an iconoclastic misanthrope, she had to admit that her adversary's discovery was radtastic.
by Bradley Darren Davidson November 14, 2006
by Devin Starr May 15, 2009
Somebody who is all out awesome and portrays a certain image that is accepted through certain groups, cults; etc.
"I love you! You're so radtastical!."
by Samantha Sadler March 6, 2006