Extremely imaginative or wildly fanciful; seemingly impossible or beyond belief; extravagantly designed or created.
From Greek 'phantastikos' meaning 'of the imagination', derived from 'phantazein' meaning 'to make visible'. Added to 'fantastic' is the suffix '-al' for emphasis.
Fantasy writing is fantastical by definition, but the most interesting fantasies (like Harry Potter) are fantastical within their own strict rules, making them paradoxically more believable.
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