very good, successful, or impressive [= amazing]:
The opportunities are unbelievable.
an unbelievable talent
very bad or shocking [= terrible]:
The pain was unbelievable.
acts of unbelievable cruelty
It was unbelievable that we were expected to pay twice.
so extreme that it hardly seems possible:
He's so lazy it's unbelievable.
an unbelievable speed
very difficult to believe and therefore probably untrue:
Yvonne's excuse for being late was totally unbelievable.
an unbelievably bad movie