Machinery .

any of various rings or eyelets of metal or the like.

an insulated washer of rubber or plastic, inserted in a hole in a metal part to prevent grounding of a wire passing through the hole.

Nautical .

a ring or strop of fiber or wire; becket.

a ring having a thickness of three strands, made by forming a loop of a single strand, then laying the ends around the loop.

a ring of fiber used as a seal or gasket, as under the head of a bolt.

a washer or packing for sealing joints between sections of pipe.

Military . a stiff ring of rubber or metal inside the top of a service cap, designed to keep the top of the cap stretched flat.

a metal-bound eyelet in cloth, sometimes used decoratively, as on a garment.

to fasten with a grommet.