lith·i·fy \ˈ ̷ ̷ ̷ ̷ˌfī\verb (-ed/-ing/-es) Etymology:lith- + -ify transitive verb : to change to stone : petrify < coal is carbonized and lithified vegetation — H.A.Meyerhoff > intransitive verb : to become changed into stone < sands lithify into sandstones — C.M.Nevin >