Also found in: Encyclopedia, Wikipedia.
Related to preignition: Spark knock
The ignition of fuel in an internal-combustion engine before the spark passes through the fuel, resulting from a hot spot in the cylinder or from too great a compression ratio for the fuel.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
pre•ig•ni•tion(ˌpri ɪgˈnɪʃ ən)
ignition of the charge in an internal-combustion engine earlier in the cycle than is compatible with proper operation.
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.