from The Century Dictionary and Cyclopedia
- n. A form of ring, used by jewelers and others, in which a segment of the circumference of the ring can be slid round upon the adjacent portion, so as to open the ring to receive a closed link or ring. The movable segment snaps back into place by a spring, and locks in place by fitting into or over the segment against which the spring presses it.
- n. A ring which is snapped into place; a cast-iron ring cut at only one point, used for packing an engine-piston. It is expanded to pass the end of the piston and snaps into place.
Sorry, no etymologies found.
Something is lacking -- it is the snap-ring that we so remember from boyhood wood-cutting days in
Instructables user cowscankill did, with a salvaged snap-ring mechanism and riveted leather hinges.