unbelievable

What it means

1. literallyNot 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.’

   1996, Colin Thompson, “Four Pigeons”, in Venus the Caterpillar and Further Wild Stories, London: Hodder Children’s Books, →ISBN, page 24

   Synonyms: beyond belief, incredible, noncredible · Antonyms: believable, credible

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

   This restaurant makes unbelievable pizza!

   4 more examples

   The most unbelievable thing happened to me today!

   Whether you want the unbelievablest sheer of chiffon . . . or the most durable of service weight . . . I’ve concluded, after a round of looking, that these stores give you a real money’s worth!

   1932 February 6, Virginia Chumley, “Visits with Virginia”, in The Chattanooga News, volume XLIV, number 189, Chattanooga, Tenn., →ISSN, →OCLC, page 11, column 6

   In other words—join the gpo and hear the world; have fun; talk to the wildest, craziest, simply unbelievablest people.

   1967, New Society, volume 9, London, →ISSN, →OCLC, page 680, column 1

   The unbelievablest (to coin a word) thing about this animation is the fact that it is generated in real time, like a video game!

   2010 March 9, Emily Lakdawalla, “Unbelievably spectacular flight through Candor Chasma”, in The Planetary Society, Pasadena, Calif., archived from the original on 06 Aug 2020

   Synonyms: incredible

3. Implausible or improbable.

   His excuse seems rather unbelievable.

   Synonyms: improbable, infeasible, unlikely · Antonyms: feasible, likely, plausible, probable

In a sentence

‘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.’

1996, Colin Thompson, “Four Pigeons”, in Venus the Caterpillar and Further Wild Stories, London: Hodder Children’s Books, →ISBN, page 24

Where it comes from

From un- + believable.