running board

English Thesaurus

1. a narrow footboard serving as a step beneath the doors of some old cars (noun.artifact)

hypernym	:	footboard,
definition	:	a narrow platform on which to stand or brace the feet (noun.artifact)

part meronym	:	auto, automobile, car, machine, motorcar,
definition	:	a motor vehicle with four wheels; usually propelled by an internal combustion engine (noun.artifact)