Synonyms of insoluble

insoluble

adjective

(ˌ)in-ˈsäl-yə-bəl 

as in impossible

incapable of being solved or accomplished

the seemingly insoluble mystery concerning the identity of the people who built these ancient structures

Synonyms & Similar Words

• impossible
• hopeless
• unlikely
• problematic
• insolvable
• unsolvable
• insuperable
• futile
• unattainable
• impractical
• unrealizable
• undoable
• useless
• incredible
• absurd
• unworkable
• impracticable
• unusable
• questionable
• infeasible
• dubious
• improbable
• suspect
• inconceivable
• debatable
• unfeasible
• disputable
• suspicious
• implausible
• fishy
• unthinkable
• shaky
• unimaginable
• unbelievable
• doubtful
• ridiculous
• far-fetched
• doubtable
• outlandish
• shady
• preposterous
• fantastic

Antonyms & Near Antonyms

• soluble
• possible
• feasible
• workable
• practical
• achievable
• attainable
• useful
• applicable
• functional
• reasonable
• usable
• resolvable
• practicable
• working
• realizable
• probable
• serviceable
• likely
• doable
• acceptable
• plausible
• conceivable
• credible
• believable

Example Sentences

Recent Examples of insoluble

Flax is known to promote good digestive health and prevent constipation, thanks to plenty of insoluble fiber and soluble fiber (both of which facilitate digestion and regular bowel movements through slightly different means). —Christina Chaey, Bon Appetit Magazine, 30 Sep. 2025

Questions the younger Kant had answered glibly were now declared insoluble. —Shai Tubali, Big Think, 30 Sep. 2025

Whole foods rich in both soluble and insoluble fiber include oats, prunes, kiwis, legumes, leafy vegetables, pears and whole grains. —Daryl Austin, USA Today, 6 Sep. 2025

Resolution of this tragic dynamic appears insoluble. —David Marks, The Orlando Sentinel, 8 Aug. 2025