Here's how it works:
* -lith- means "stone"
* -iasis means "condition of"
Therefore, -lithiasis refers to a condition characterized by the presence of stones, particularly in a body organ or structure.
For example:
* Cholelithiasis: Presence of stones in the gallbladder
* Nephrolithiasis: Presence of stones in the kidney
* Urolithiasis: Presence of stones in the urinary tract