unsoluble

/ʌnˈsɑːljəbəl/
adjective
  1. Not able to be dissolved in a liquid.
    • The chemist tested whether the powder was soluble or unsoluble in alcohol.
    • Sand is unsoluble in water, so it settles at the bottom.
    • Some minerals are unsoluble in acid, making them hard to analyze.
  2. Not able to be solved or explained; insoluble (of a problem or mystery).
    • The math problem was unsoluble with the methods they had learned.
    • They faced an unsoluble conflict between their personal values and their job duties.
    • The ancient riddle seemed unsoluble to even the wisest scholars.
Synonyms
What does "unsoluble" mean? | whatsthatwordmean | whatsthatwordmean