'Piston ring' definitions:
Definition of 'piston ring'
From: WordNet
noun
Seal consisting of a split metal ring that seals the gap between a piston and the cylinder wall
Definition of 'Piston ring'
From: GCIDE
- Piston ring \Pis"ton ring\ (Mach.) A spring packing ring, or any of several such rings, for a piston. [Webster 1913 Suppl.]