Smart answer:

Your search for What is an oasis returned the following results:

an isolated area in a desert

An oasis is an isolated area in a desert, typically surrouding a water source, such as a pond or small lake.

Source:

a place in the desert that has water and is fertile

An oasis is a place in the desert that has water and is fertile.

Source:

a place in a desert that has water supplied by a spring or other underground water source

An oasis is a place in a desert that has water supplied by a spring or other underground water source.

Source:

one of the oldest pre-Saharan cities and an outstanding example of a traditional settlement

an oasis is one of the oldest pre-Saharan cities and an outstanding example of a traditional settlement.

Source: