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

This includes soluble fiber, which increases healthy gut bacteria and lowers cholesterol and blood sugar levels, and insoluble fiber, which improves bowel health, says Howman. — Kirsten Nunez, Martha Stewart, 4 July 2026

The insoluble character of Alfa’s best records is reflected in his biography, which is difficult to neatly summarize. — H.d. Angel, Pitchfork, 16 June 2026

Bananas have soluble and insoluble fiber, both important types, Valente shares. — Alexandra Frost, USA Today, 12 June 2026

Most whole foods, like fruits, vegetables, and whole grains, contain a combination of insoluble and soluble fibers, but some are more concentrated in one than the other. — Jillian Kubala, Health, 29 May 2026