noun
Refers to a stone monument, often a gravestone or memorial stone. More formal than 墓石 (ぼせき) and can be used for non-grave monuments.
公園に古い碑石が立っている。
An old stone monument stands in the park.
墓地には多くの碑石が並んでいた。
Many gravestones were lined up in the cemetery.
Compound of 碑 (ひ, 'monument') and 石 (せき, 'stone'). The reading ひせき uses the on'yomi for both characters.