Simple Definition of unheard–of
: not known to have existed or happened before : very unusual
Full Definition of unheard–of
: previously unknown; especially : unprecedented <moving at unheard–of speeds>
First Known Use of unheard–of
UNHEARD–OF Defined for Kids
Definition of unheard–of
: not known before <an unheard-of invention>
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Spanish Central: Translation of "unheard–of"
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