Tailgate

v. follow an automobile very closely, travel closely behind another vehicle

n. hinged section at the rear of a vehicle that can be lowered during loading or unloading

The tailgate in American English is the board or gate at the back of a wagon, truck, station wagon, etc., hinged at the bottom which can be removed or let down for convenience in loading or unloading. A door at the back of a vehicle hinged at the top and opens to the top is referred to in American English as hatch, hatchback or liftgate.
See more at Wikipedia.org...

Noun
1. a gate at the rear of a vehicle; can be lowered for loading
(synonym) tailboard
(hypernym) gate
(part-holonym) beach wagon, station wagon, wagon, beach waggon, station waggon, waggon
Verb
1. follow at a dangerously close distance; "it is dangerous to tailgate another vehicle"
(hypernym) follow
(derivation) tailgater

The outlet of a natural gas processing plant where dry residue gas is delivered or redelivered for sale or transportation. (DOE5)

A gate located at the downstream of a lock in the tailwater of a dam. (TNDOT1)

drive too close to the car in front, on his tail The instructor told me not to tailgate - to leave more space.