Main Entry:

spark plug

Function:

noun

Date:

1903

1 : a part that fits into the cylinder head of an internal combustion engine and carries two electrodes separated by an air gap across which the current from the ignition system discharges to form the spark for combustion 2 : one that initiates or gives impetus to an undertaking

— spark·plug \ˈspärk-ˌpləg\ transitive verb