The outskirts are the far edges of a city, where the buildings thin out. On the outskirts, the outskirts of town, reach the outskirts.
It is plural only and always takes the definite article. Where the outskirts end is a matter of feeling rather than any boundary, since city limits and built-up areas rarely agree. The word carries a slight sense of nowhere in particular.
1nounoutskirtsThe far edges of a city, where the buildings thin out.
“They live on the outskirts of the city, where the rents are cheaper and there are fields.”
outskirts is an edge.
From out- + skirts.
Etymology from Wiktionary, CC BY-SA