Definition of metacryst in US English:

metacryst

noun

Geology
  • A large crystal formed in a metamorphic rock by recrystallization, surrounded by a finer-grained groundmass of other metamorphic crystals; a porphyroblast.

Origin

Early 20th century. From meta- + cryst-, after phenocryst, xenocryst.

Pronunciation

metacryst

/ˈmɛtəkrɪst/