implausibly adv. + Add to list US //ˌɪmˈpɫɔzəbɫi// UK //ɪmplˈɔːzəbli// im·plau·si·bly SynonymsAntonymsEtymology Synonyms improbablyincrediblyunbelievably Antonyms believablycrediblyOrigin From implausible + -ly.