unbelievable

adj

Etymology: From un- + believable.

1. Not to be believed.

   “‘Come on, girls,’ said Steve, ‘be honest, we won.’ / ‘Yeah,’ said Raymond, ‘we let you off because you’re girls.’ / ‘You’re unbelievable,’ said Liz. / ‘Well, if we’re unbelievable,’ said Steve, ‘then you’re unbelievabler.’”

2. Amazing, astonishing; so surprising that one is almost, or figuratively, unable to believe.

   “The most unbelievable thing happened to me today!”

   “This restaurant makes unbelievable pizza!”

3. Implausible or improbable.

   “His excuse seems rather unbelievable.”