insoluble

/ɪnˈsɑljəbəl/
adjective
  1. Unable to be dissolved in a liquid, especially water.
    • The chemist tested whether the powder was soluble or insoluble in alcohol.
    • Sand is insoluble in water, so it sinks to the bottom.
    • Some vitamins are fat-soluble, while others are insoluble in oil.
  2. Impossible to solve or explain; having no solution.
    • The ancient riddle seemed insoluble until a child solved it.
    • Some math problems are insoluble with current methods.
    • For years, the mystery of the missing painting remained insoluble.
What does "insoluble" mean? | whatsthatwordmean | whatsthatwordmean