n.

1. 着火；燃烧[U]
   The ignition of the forest was caused by lightning.

   森林起火是由雷电引起的。

2. 【机】点火，发火；点火开关，发火装置[the S]
   turn on the ignition

   开点火开关

3. 【化】灼烧[U]

n.

1. the action of igniting or the state of being ignited.
2. the starting of the combustion of fuel in the cylinders of an internal-combustion engine.