Final answer:
The least desirable lot bordered by the backs of other lots is known as a T-intersection lot, which is often less sought-after due to exposure to car headlights and reduced privacy.
Step-by-step explanation:
The least desirable lot, bordered on the side by the backs of lots that front on another street, is commonly referred to as a T-intersection lot. Unlike a key lot, which typically has added value due to its position adjacent to a corner lot, the T-intersection lot is often less desirable because it is exposed to the headlights of cars when they turn at the T-intersection, and it can suffer from a lack of privacy due to its positioning. Choosing a lot involves considering a variety of factors such as location, privacy, and traffic exposure, which can greatly affect the appeal and value of the property.