1. ludicrously odd;
2. extraordinarily good; used especially as intensifiers;
3. extravagantly fanciful and unrealistic; foolish;
- "a fantastic idea of his own importance"
4. existing in fancy only;
- "fantastic figures with bulbous heads the circumference of a bushel"- Nathaniel Hawthorne
- synonym： fantastical
5. exceedingly or unbelievably great;
- "the bomb did fantastic damage"
- "Samson is supposed to have had fantastic strength"
- "phenomenal feats of memory"
- synonym： phenomenal