Source : Webster's Revised Unabridged Dictionary (1913)

Spark coil \Spark coil\ (Elec.)
   (a) An induction coil, esp. of an internal-combustion engine,
       wireless telegraph apparatus, etc.
   (b) A self-induction coil used to increase the spark in an
       electric gas-lighting apparatus.

Source : WordNet®

spark coil
     n : an induction coil used to create sparks