unheard–of

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adjective un·heard–of \ˌən-ˈhərd-ˌəv, -ˌäv\

Definition of unheard–of

  1. :  previously unknown; especially :  unprecedented moving at unheard–of speeds

First Known Use of unheard–of

1592


UNHEARD–OF Defined for English Language Learners

unheard-of

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adjective

Definition of unheard–of for English Language Learners

  • : not known to have existed or happened before : very unusual


UNHEARD–OF Defined for Kids

unheard–of

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adjective un·heard–of \ˌən-ˈhərd-ˌəv, -ˌäv\

Definition of unheard–of for Students

  1. :  not known before an unheard-of invention


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