胃石 is read as いせき (iseki) and means gastrolith.
いせき
iseki
い
Chinese "stomach" constellation (one of the 28 mansions)
いぶくろ
dietary needs
いつう
stomach-ache
いかめら
endoscope
いせつじょじゅつ
gastrectomy
ほうせき
gem
こうせき
ore
ふせき
strategic arrangement of go stones at the beginning of a game
がんせき
rock
さいせき
quarrying
やけいし
hot stone
かるいし
pumice stone