Merriam-Webster Logo
SINCE 1828
Menu
dictionary thesaurus

unsubstantiate

transitive verb
un·​substantiate | \ "+\

Definition of unsubstantiate

: to divest of substantiality : make unsubstantial

Love words?

You must — there are over 200,000 words in our free online dictionary, but you are looking for one that’s only in the Merriam-Webster Unabridged Dictionary.

Start your free trial today and get unlimited access to America's largest dictionary, with:

  • More than 250,000 words that aren't in our free dictionary
  • Expanded definitions, etymologies, and usage notes
  • Advanced search features
  • Ad free!

History and Etymology for unsubstantiate

un- entry 2 + substantiate

Keep scrolling for more

Learn More about unsubstantiate

Statistics for unsubstantiate

Look-up Popularity

Comments on unsubstantiate

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

Show Comments  Hide Comments 

WORD OF THE DAY

sporadic

Listen to the pronounciation of sporadic

not constant or steady

Get Word of the Day daily email!

Test Your Vocabulary

Summer 2019 Words of the Day Quiz

  • a-bowl-of-peach-sorbet-with-cut-peaches-next-to-it
  • Which is a synonym of desideratum?
True or False

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

TAKE THE QUIZ
Word Winder's CrossWinder

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!

Words at Play
Ask the Editors
Word Games