ETYM Latin fabulosus; cf. French fabuleux. Related to Fable.
1. Barely credible.
2. Based on or told of in traditional stories; lacking factual basis or historical validity; SYN. mythic, mythical, mythologic, mythological.
3. Extremely pleasing; SYN. fab.

So celebrated as to having taken on the nature of a legend

In a fabulous manner; SYN. fantastically.