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2.
Adj. Rocktastic: A Portmanteau combination of two words "rock and fantastic" meaning beyond fantastic;or ridiculously wonderful; it is as long lasting as a rock or as exciting as rock n' roll with an extra dose of fantastic.

Rock~ rock is a naturally occurring aggregate of minerals and/or mineraloids.

Also, more importantly also refers to rock 'n' roll: a genre of popular music originating in the 1950s; a blend of black rhythm-and-blues with white country-and-western; "rock is a generic term for the range of styles that evolved out of rock'n'roll."

Fantastic~ antic: ludicrously odd; extraordinarily good or great ; used especially as intensifiers; fanciful and unrealistic; foolish;existing in fancy only;extravagantly fanciful in design, construction, appearance;is a literary term that describes a quality of other literary genres, and in some cases is used as a genre in and of itself, although in this case it is often conflated with the Supernatural; Existing in or constructed from fantasy; of or related to fantasy; fanciful; Not believable; implausible; seemingly only possible in fantasy; Wonderful; marvelous; excellent; extraordinarily good or great (used especially as an intensifier)
"Your outfit is so rocktastic. Everybody is going to love the way you look."

"This is an awesome show/concert were going to go see. We are sooo gonna have a rocktastic time."

"I just got a degree... resp: Congratulations! That is truly rocktastic."

"That fantasy or sci-fi movie, game, book, (insert some kind of entertainment or media) was fraken rocktastic."
by Mystic Model May 19, 2009
 
1.
music that rocks fantastically.
anything that you makes you get up and want to rock out.
by Ed Hartley January 13, 2004
 
4.
You are so excited and fascinated, you can't say a word and are still like a rock.
Were goiNg to Disneyland! Oh my god I'm rocktastic
by TheAwesomeNoob December 22, 2010
 
6.
When something or someone both Rocks and is fantastic
Stacey is Rocktastic- because she Rocks and is fantastic
by right R January 07, 2013