In internal-combustion engines with electric ignition, a plug, screwed into the cylinder head, having through it an insulated wire which is connected with the induction coil or magneto circuit on the outside, and forms, with another terminal on the base of the plug, a spark gap inside the cylinder.
Webster's Revised Unabridged Dictionary
| APA | Webster's. (2011). spark plug. Retrieved September 20, 2026, from http://smartdefine.org/spark_plug/definitions/2064441 |
| Chicago | Webster's. 2011. "spark plug" http://smartdefine.org/spark_plug/definitions/2064441 (accessed September 20, 2026). |
| Harvard | Webster's 2011, spark plug, Smart Define, viewed 20 September, 2026, <http://smartdefine.org/spark_plug/definitions/2064441>. |
| MLA | Webster's. "spark plug" 28 May 2011. Web. 20 September 2026. <http://smartdefine.org/spark_plug/definitions/2064441> |