Informal. the body of an animal killed on a road by a motor vehicle.
Origin of road kill
An Americanism dating back to 1970–75
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
mainly US the remains of an animal or animals killed on the road by motor vehicles
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
animal killed by vehicular traffic, 1972; the figurative sense is from 1992.
Online Etymology Dictionary, © 2010 Douglas Harper