Tailgating

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

Tailgating is the practice of driving on a road too closely behind another vehicle, such as less than the travel distance in two seconds or equivalently, one vehicle-length for every 8 km/h (5 mph) of the current speed. In most cases this is done out of frustration toward, or in order to help get past, a slower moving vehicle which is supposedly, but not always, impeding the progress of the vehicle behind it. Some slower vehicles will not speed up or pull over when the situation arises; this is seen as selfish behaviour by tailgaters, and may also be illegal in some jurisdictions due to its increased potential for causing a car accident. On the other hand, tailgating could also be seen as not only selfish, but unnecessarily risky, as it could cause the vehicle directly in front of the tailgater to crash. Tailgating is also illegal in some jurisdictions due to increased risks of causing an accident.
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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

Practice whereby a broker purchases a security after placing an order for the same security for a customer. The broker hopes to profit either because of information which the customer has or because the customer's purchase is of sufficient size to affect security prices. This is an unethical practice.

Driving too closely behind the vehicle ahead. (ATA1)