Strip of dirt between the sidewalk and the street, notoriously hard to grow plants of any kind in due to several factors: lack of water, heat reflected from paved surfaces, foot traffic, trash, dog crap, and salt from winter snowmelt. Also called a tree lawn, inferno strip, devil strip
Most hell strips are public property that must be maintained by the property owner. That means the city can do whatever it wants to your hell strip - put in water and sewer lines or bus benches, pile snow on it, tear it up during street repairs and widening. In some cities you can be fined for not maintaining your hell strip, and in some HOA communities you must plant trees and grass in it and keep it watered.
The term is most often attributed to garden writer Lauren Springer, who popularized the practice of planting tough, drought-tolerant plants (including cactus) on hell strips. Now there are "planned" hell strip gardens offered by many nurseries.
When I get done landscaping the yard, I'll think about planting the hell strip.
Most gardeners find their "hell strip" to be that spot next to the sidewalk or the street that people's dogs potty on and gets blasted with full sun from 9 a.m. to 7 p.m. and the sprinkler system doesn't quite reach.