bumper–to–bumper adjective
: made up of long lines of cars that are very close to each other
▪ bumper-to-bumper traffic ▪ The cars on the highway were bumper-to-bumper. [=the cars were very close to each other]
▪ bumper-to-bumper traffic ▪ The cars on the highway were bumper-to-bumper. [=the cars were very close to each other]
