laccolith
noun
lac·co·lith ˈla-kə-ˌlith 
: a mass of igneous rock that is intruded between sedimentary beds and produces a domical bulging of the overlying strata
laccolithic
ˌla-kə-ˈli-thik
adjective 
Example Sentences
Recent Examples on the Web This is the language of Big Sky Country: laccolith, dike, shonkinite, marine shale. 
Porter Fox, Outside Online, 1 June 2018
Porter Fox, Outside Online, 1 June 2018 Word History
Etymology
Greek lakkos pond, reservoir + English -lith — more at lake
First Known Use
1880, in the meaning defined above