clathr-, clathro- +
(Greek > Latin: bars, lattice, grate; used in the sense of "lattice[d], latticelike")
2. A complex in which an atom or molecule of one substance is surrounded by a crystal lattice of another one.
In the context of this word, a lattice is a regular, periodic configuration of points, particles, or objects throughout an area or a space; especially, the arrangement of ions or molecules in a crystalline solid; such as, the spatial arrangement of fissionable and nonfissionable materials in a nuclear reactor.
Such hydrates exist at higher pressures in glaciers where air bubbles trapped in the process of firn formation (old snow that has become granular and compacted or dense) near the surface and appear to dissolve in the ice.