myth·i·cal – [mith-i-kuhl]

adjective
1. pertaining to, of the nature of, or involving a myth.
2. dealt with in myth,  as a prehistoric period.
3. dealing with myths,  as writing.
4. existing only in myth,  as a person.
5. without foundation in fact; imaginary; fictitious: The explanation was entirely mythical.
Also, myth·ic.

Origin:
1670–80;  < Late Latin mȳthicus  < Greek mȳthikós  of myths ( see myth, -ic) + -al1