To be Incredibly amazing, both RADical and fanTASTIC at the same time.
Bob: Hey, Guess what cindell, it's friday.

Cindell: AGAIN??? ARE YOU SERIOUS??

Bob: yep.

Cindell: OH MAN, THAT's SO RADTASTIC, I HARDLY KNOW WHAT TO DO WITH MYSELF!!
by Cindell Corbeil November 20, 2007
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(adj.) a word that describes something that is so far beyond amazing that this is the only word to describe it.
Teacher: Does anyone know what the synonym for-

Jack: RADTASTICAL!

Teacher: No, Jack. And you really should really start raising your hand-

Jack: -BUT, I DO!

Teacher: Yes, Jack. AS you're blurting out what you have to say. So does anyone know the synonym for- oh- I guess you're right, Jack.

Jack: RADTASTICAL *:D*
by bleyw&trippy January 8, 2010
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a word derived from the words "RAD"(commonly all capitalized) and "fantastic", in a way of saying better then RAD or Fantastic but in the sense of being rad or fantastic
RADtastic mainly used in small towns or areas made up in the city of Bellevue Nebraska while describing SKA music
a commonly used phrase with RADtastic is
"RADtastically SKAwesome"
"Dude, thats RADtastic!"
"RADtastically SKAwesome
by RADtastically SKAwesome January 11, 2007
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Extremely rad.
Really "cool".
Amazing.
Sarah is radtasic.
Ashley, that stunt was so "rad". Radtastic
Tonight is going to be so radtsatic.
Tonight is going to be so rad.
by Holly. October 7, 2007
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