improbability

UK: /ɪmˌprɒbəˈbɪlɪti/

US: /ɪmˌprɑbəˈbɪlɪti/

US: (im prob′ə bil′i tē, im′prob-)

Inflections of 'improbability' (n): npl: improbabilities

WordReference Random House Unabridged Dictionary of American English © 2025

im•prob•a•bil•i•ty  (im prob′ə bil′i tē, im′prob-), n., pl. -ties for 2.

1. the quality or condition of being improbable;
   unlikelihood.
2. something improbable or unlikely.

• improbable + -ity 1590–1600

WordReference Random House Learner's Dictionary of American English © 2025

im•prob•a•ble /ɪmˈprɑbəbəl/   adj. 

1. not probable; unlikely to be true or to happen:
   an improbable ending to a story.
   [ it + be + ~ + that clause]:
   It's improbable that we should win ten straight games.

im•prob•a•bil•i•ty /ɪmˌprɑbəˈbɪlɪti/  n. [countable]
im•prob•a•bly, adv. See -prob-.

WordReference Random House Unabridged Dictionary of American English © 2025

im•prob•a•ble  (im prob′ə bəl), adj. 

1. not probable;
   unlikely to be true or to happen:
   Rain is improbable tonight.

• Latin improbābilis. See im-², probable
• 1590–1600

im•prob′a•bly, adv. 
im•prob′a•ble•ness, n. 
Synonyms

questionable, doubtful, implausible.