A periodic optical nanostructure that affects the motion of photons in much the same way that ionic lattices affect electrons in solids.

Glass that contains at least 24% lead oxide (PbO). / Cut glass made of this material.

Alternative form of anticrystal

Alternative form of quasicrystal

A temperature-controlled chamber used to maintain the quartz crystal in electronic crystal oscillators at a constant temperature, in order to prevent changes in the frequency due to variations in ambient temperature.

plural of crystal oven

plural of cryfest

(informal) Something sad or moving, especially a film. / (informal) An episode of intense crying.

(anatomy) An intestinal gland.

(geology, of a subsurface horizon) perennially frozen