unheard-of

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

Definition of unheard-of

: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

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

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

Definition of unheard-of for Students

:not known before an unheard-of invention


Seen and Heard

What made you want to look up unheard-of? Please tell us where you read or heard it (including the quote, if possible).

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

WORD OF THE DAY

cautious about doing something

Get Word of the Day daily email!

Test Your Vocabulary

Forms of Government Quiz

  • knupfer-painting-solon-before-croesus
  • A gerontocracy is rule by:
True or False

Test your knowledge - and maybe learn something along the way.

TAKE THE QUIZ
SCRABBLE® Sprint

Test Your Knowledge - and learn some interesting things along the way.

TAKE THE QUIZ

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!