Muriel, maybe, with advert for engine part

WordNet Word definitions in WordNet
n. electrical device that fits into the cylinder head of an internal-combustion engine and ignites the gas by means of an electric spark [syn: sparking plug , plug ]

Wikipedia Word definitions in Wikipedia
A spark plug (sometimes, in British English , a sparking plug , and, colloquially, a plug ) is a device for delivering electric current from an ignition system to the combustion chamber of a spark-ignition engine to ignite the compressed fuel/air mixture ...

Longman Dictionary of Contemporary English Word definitions in Longman Dictionary of Contemporary English
noun EXAMPLES FROM CORPUS ▪ Always remove the lead from the spark plug of petrol machines and unplug electric models before cleaning or servicing. ▪ For the sake of the team, she is willing to be the spark plug . ▪ He was a spark plug at the top of the ...

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
Spark plug \Spark plug\ In internal-combustion engines with electric ignition, a plug, screwed into the cylinder head, connected with the induction coil or magneto circuit on the outside, and used to produce a spark to ignite the fuel-air mixture in the ...

Wiktionary Word definitions in Wiktionary
n. The part of an internal combustion engine which forms a high-voltage electric spark which ignites the fuel-air mixture to begin the power stroke.