grommet /(grŏm"mĕt)/

grom·met

grommet

n.
  1. A ring formed by twisting on itself a single strand of an unlaid rope. Sometimes written grummet.
  2. Any eyelet or ring of metal or other material inserted in a hole in a sheet of some other material; in sailing, a metallic ring in or for a sail or a mailbag.
  3. A ring of rubber or other insulating material inserted in a hole in some surface of a device, to prevent wires passing through the hole from making contact with the surface; used especially in electrical and electronic devices, to prevent undesired electrical contact.
  4. A ring of rope used as a wad to hold a cannon ball in place. (Mil.)