Filled cable
In telecommunication, a filled cable is a cable that has a non-hygroscopic material, usually a gel called icky-pick, inside the jacket or sheath. The nonhygroscopic material fills the spaces between the interior parts of the cable, preventing moisture from entering minor leaks in the sheath and migrating inside the cable.
A metallic cable filled with a dielectric material, such as a coaxial cable or a metal waveguide, is not considered to be a "filled cable".
References
This article incorporates public domain material from Federal Standard 1037C. General Services Administration. Archived from the original on 2022-01-22. (in support of MIL-STD-188).
Further reading
See Telcordia GR-421-CORE, Generic Requirements for Metallic Telecommunications Cables, for filled, polyolefin-insulated conductor (PIC) cable requirements.