[aw-toh-ig-nish-uh n]
  1. Automotive. the spontaneous ignition of fuel when introduced into the combustion chamber of an internal-combustion engine, as a result either of glowing carbon in the chamber or of the heat of compression.
  2. spontaneous combustion.

Origin of autoignition Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018