Diesel

Noun

 * 1) A fuel derived from petroleum (or other oils) but heavier than gasoline/petrol. Used to power diesel engines which burn this fuel using the heat produced when air is compressed.
 * 2) A vehicle powered by a diesel engine.

Verb

 * 1) To ignite a substance by using the heat generated by compression.
 * 2)  For a spark-ignition internal combustion engine to continue running after the electrical current to the spark plugs has been turned off.  This occurs when there's enough heat in the combustion chamber to ignite the air/fuel without a spark, the same way heat and pressure cause ignition in a diesel engine.
 * The only reason the VW bug has a solenoid is to prevent it from dieseling.