Definition of fantastic
1 a : based on fantasy (see 1fantasy 3) : not real
b : conceived or seemingly conceived by unrestrained fancy
"fantastic new space and nuclear weapons" —Jack Raymond
c : so extreme as to challenge belief : unbelievable
a fantastic industrial complex of steel, coal, machine tools, and other heavy industries —M. S. Handler
; broadly : exceedingly large or great spent fantastic sums on his library
2 : marked by extravagant fantasy or extreme individuality : eccentric fantastic works of art
1 a : based on fantasy (see 1fantasy 3) : not real
b : conceived or seemingly conceived by unrestrained fancy
"fantastic new space and nuclear weapons" —Jack Raymond
c : so extreme as to challenge belief : unbelievable
a fantastic industrial complex of steel, coal, machine tools, and other heavy industries —M. S. Handler
; broadly : exceedingly large or great spent fantastic sums on his library
2 : marked by extravagant fantasy or extreme individuality : eccentric fantastic works of art