ignition

noun

1. a setting on fire or catching on fire
2. the means by which a thing is ignited
3. in an internal-combustion engine,
   1. the igniting of the explosive mixture in the cylinder
   2. the device or system for doing this; esp. the key-operated switch
4. Chem. the heating of a compound or mixture to the point of complete combustion, complete chemical change, or complete removal of volatile material

adjective