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un·heard-of | \ ˌən-ˈhərd-ˌəv 
, -ˌäv \
, -ˌäv \Definition of unheard-of
: previously unknown especially : unprecedented moving at unheard-of speeds
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More Definitions for unheard-of
unheard-of
adjectiveEnglish Language Learners Definition of unheard-of
: not known to have existed or happened before : very unusual
See the full definition for unheard-of in the English Language Learners Dictionary
unheard-of
adjectiveun·heard-of | \ ˌən-ˈhərd-ˌəv, -ˌäv \
Kids Definition of unheard-of
: not known before
an unheard-of invention
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Time Traveler for unheard-of
The first known use of unheard-of was in 1592
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