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Synonyms

groundless

American  
[ground-lis] / ˈgraʊnd lɪs /

adjective

  1. without rational basis.

    groundless fears.

    Synonyms:
    idle, unjustified, unfounded, baseless

groundless British  
/ ˈɡraʊndlɪs /

adjective

  1. without reason or justification

    his suspicions were groundless

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Other Word Forms

  • groundlessly adverb
  • groundlessness noun

Etymology

Origin of groundless

before 900; Middle English: bottomless, unfathomable; Old English grundlēas. See ground 1, -less

Explanation

Something that's groundless isn't valid or justified, like your groundless fear that you failed your math quiz, even though you studied and knew all the material. Grounds are "factors forming the justification for a belief," and when you don't have any such grounds, your belief is groundless. In other words, anything groundless has no reason or cause to back it up. A groundless claim is one that has no proof, and a groundless suspicion is empty: "We questioned that nice lady next door and made her cry, thanks to your groundless accusation that she stole our cat."

Keep Reading on Vocabulary.com

Vocabulary lists containing groundless

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

A Kremlin spokesman rejected the allegations as groundless.

From The Wall Street Journal • Dec. 12, 2025

China accused Britain's Keir Starmer of making "groundless accusations" on Tuesday, a day after the prime minister said he would engage with Beijing but warned China posed a national security threat.

From Barron's • Dec. 2, 2025

Marinakis, who was represented by his lawyer Vassilis Dimakopoulos in court, and the other Olympiacos board members have dismissed misdemeanour charges as groundless.

From BBC • Nov. 5, 2025

Lot of reasons for that, it’s not groundless optimism.

From Salon • Aug. 5, 2025

It was with a heavy heart that Frodo saw Aragorn and Legolas climb the steep bank and vanish into the mists; but his fears proved groundless.

From "The Fellowship of the Ring" by J.R.R. Tolkien