1.  spark gap(n = noun.artifact) - a component of an ignition system; consists of two shaped electrodes and the space between them;
is a kind of component, constituent, element
is a part of ignition, ignition system

2.  spark gap(n = noun.artifact) - the gap between two high-potential terminals;
is a kind of crack, gap
is a part of induction coil

   The space filled with air or other dielectric between high potential terminals (as of an electrostatic machine, induction coil, or condenser), through which the discharge passes; the air gap of a jump spark. [Webster 1913 Suppl.]

air gap, credibility gap, cumberland gap, dame muriel spark, gap, generation gap, jump spark, muriel sarah spark, muriel spark, narrow the gap, spark, spark advance, spark arrester, spark chamber, spark coil, spark counter, spark lever, spark of life, spark off, spark plug, spark transmitter, trade gap, water gap, wind gap