INSOL'UBLE, adjective [Latin insolubilis; in and solvo, to dissolve.] 1. That cannot be dissolved, particularly by a liquid. We say a substance is insoluble in water, when its parts will not separate and mix with that fluid. 2. Not to be solved or explained; not to be resolved; as a doubt or difficulty. [Not much used.]
Source: Webster's 1828 American Dictionary ↗ · public-domain · returned verbatim, no AI