o-ring
UK[ˈəʊ rɪŋ]US[ˈoʊ rɪŋ]
n
A flat ring made of rubber or plastic, used as a seal in mechanical joints to prevent the escape of a fluid or gas.
Etymology
The term "O-ring" is a modern technical compound, coined in the 20th century to describe a specific gasket or seal. Its logic is purely descriptive, combining the alphabetic letter "O" to denote its circular cross-section with the common noun "ring" indicating its toroidal, looped shape. This nomenclature follows a straightforward engineering tradition of naming parts by their visual form, similar to terms like "U-bolt" or "T-joint". The word has no classical etymology but is a practical, literal construction within technical English to identify a crucial component in hydraulic and pneumatic systems.
Analysis
The word is a compound formed from the letter "O" (describing the shape) and the noun "ring". "O" originates from the Greek letter omicron, used in English to denote the shape of a circle. "Ring" comes from Old English hring, meaning a circular band.
Examples
The mechanic replaced the worn o-ring to stop the oil leak.
Ensure the o-ring is properly lubricated before assembly.
A failed o-ring was the cause of the spacecraft's fuel system malfunction.