noun
insolubility
Technical term used in chemistry and materials science to describe a substance's inability to dissolve in a solvent.
この化合物の不溶性が問題となっている。
The insolubility of this compound is a problem.
Compound of 不 (fu-, 'not') + 溶性 (yōsei, 'solubility'), from 溶 (yō, 'dissolve') + 性 (sei, 'property').