space between soil particles that is relatively small and likely to be water filled (contrast with macropore).
Merriam-Webster Online Dictionary
micropore (noun) a very fine pore
micropore (Wikipedia)
A microporous material is a material containing pores with diameters less than 2 nm. Examples of microporous materials include zeolites and metal-organic frameworks.
Porous materials are classified into several kinds by their size. The recommendations of a panel convened by the International Union of Pure and Applied Chemistry (IUPAC) are:
- microporous materials have pore diameters of less than 2 nm
- mesoporous materials have pore diameters between 2 nm and 50 nm
- macroporous materials have pore diameters of greater than 50 nm.
Micropores may be defined differently in other contexts. For example, in the context of porous aggregations such as soil, micropores are defined as cavities with sizes less than 30 μm.