lithiasis

from WordNet (r) 3.0 (2006)

lithiasis
    n 1: the formation of stones (calculi) in an internal organ

from The Collaborative International Dictionary of English v.0.48

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.
   [1913 Webster]