mesopore

in catalysis
https://doi.org/10.1351/goldbook.M03853
Pore of intermediate size. [Those with widths exceeding about \(0.05\ \unicode[Times]{x3BC}\text{m}\) or \(50\ \text{nm}\) (\(500\ \mathring{\text{A}}\)) are called macropores; those with widths not exceeding about \(2\ \text{nm}\) (\(20\ \mathring{\text{A}}\)) are called micropores].
Sources:
PAC, 1972, 31, 577. (Manual of Symbols and Terminology for Physicochemical Quantities and Units, Appendix II: Definitions, Terminology and Symbols in Colloid and Surface Chemistry) on page 585 [Terms] [Paper]
PAC, 1976, 46, 71. (Manual of Symbols and Terminology for Physicochemical Quantities and Units - Appendix II. Definitions, Terminology and Symbols in Colloid and Surface Chemistry. Part II: Heterogeneous Catalysis) on page 79 [Terms] [Paper]