microcrystalline Syllabification: (mi·cro·crys·tal·line)Pronunciation: /ˌmīkrōˈkristəlin, -ˌlīn, -ˌlēn/Definition of microcrystalline adjective (of a material) formed of microscopic crystals. microcrystalline in other Oxford dictionaries Definition of microcrystalline in the British & World English dictionary