Wiktionary
undissolved
a. Not dissolved
WordNet
undissolved
adj. retaining a solid form; "undissolved sugar in the bottom of the cup"
Usage examples of "undissolved".
On the fourth day undissolved traces of three out of the five bits could still be detected, the other two having quite disappeared.
With the bottom of his spoon, he crushed the undissolved lump of sugar in his teacup, drank off the tea in one long sip, then replaced the cup exactly in the center of the saucer.