What is "lithiasis"

Lithiasis \Li*thi"a*sis\ (l[i^]*th[imac]"[.a]*s[i^]s), n. [NL., fr. Gr. liqi`asis, fr. li`qos stone.] (Med.) The formation of stony concretions or calculi in any part of the body, especially in the bladder and urinary passages.
--Dunglison.

n. (context medicine English) The process of forming stone-like deposits or calculus formed in an internal organ, such as a gallstone in the gall bladder.

n. the formation of stones (calculi) in an internal organ