not seeming reasonable or likely to be true an implausible claim/idea/theory It was all highly implausible. Her explanation is not implausible. opposite plausible
NAmE//ɪmˈplɔzəbli//
adverb He argued, somewhat implausibly, that the accident could not have been prevented. She quoted an implausibly high figure.See implausible in the Oxford Advanced Learner's DictionaryCheck pronunciation: implausible