Definition of autolith in English:

autolith

noun

Geology
  • A piece of rock within an igneous mass which crystallized earlier than the surrounding rock, and may differ from it in composition or structure, but was formed from the same body of magma.

Origin

Early 20th century. From auto- + -lith, after xenolith.

Pronunciation

autolith

/ˈɔːtəlɪθ/