'microcrystalline' originates from Greek and Latin/French elements: the prefix 'micro-' from Greek 'mikros' meaning 'small', and 'crystalline' from Late Latin 'crystallinus' ultimately from Greek 'krystallos' meaning 'ice' or 'crystal'.

'microcrystalline' formed in modern scientific English by combining the combining form 'micro-' (used from the 19th century onward) with 'crystalline' (from Middle English 'cristalline' via Old French 'cristallin' and Latin 'crystallinus'), producing the compound used in materials and geological descriptions.

Initially the components referred simply to 'small' and 'crystal(ine)'; over time the compound came to denote specifically a material structure made up of microscopic crystals as used in chemistry, materials science, and geology.