This article is from the Chrysler-Plymouth-Dodge FAQ, by Dr. David Zatz with numerous contributions by others.
Mopar is slang for a Chrysler-produced car. Some extend it to AMCs
and to MMC products (e.g. Colt) sold by DC; and some restrict it to
high performance only. It is the name of Chrysler's parts division.
Mopar stands for MOtor PARts. MoPar is a registered trademark.