is an apparently solid, jellylike material formed from a colloidal solution. By weight, gels are mostly liquid, yet they behave like solids. An example is gelatin
communications, a gel resembling petroleum jelly
in viscosity is used to surround a fiber, or multiple fibers, enclosed in a loose buffer
tube. This gel serves to lubricate and support the fibers in the buffer tube. It also prevents water intrusion if the buffer tube is breached. Gels are also used in fiber-optics as index-matching materials.
Source: from Federal Standard 1037C and from the FAA Glossary of Optical Communications Terms