improbability UK /ɪmˌpɹɒb.əˈbɪl.ɪ.ti/US /ɪmˌpɹɑb.əˈbɪl.ə.ti/ noun2 •The quality or state of being improbable; unlikelihood. •That which is improbable; an improbable event or result. formsimprobabilities