primarypurpose
nounUK /ˈpraɪ.mə.ri ˈpɜː.pəs/
US /ˈpraɪ.mɛr.i ˈpɝː.pəs/
The main reason you do something.
The primary purpose of a school is to help children learn.
OTHER MEANINGS
2. The most important job something is made to do.
The primary purpose of a fire alarm is to warn people about danger.
3. The first or leading reason behind a plan.
Her primary purpose in joining the club was to make new friends.
4. The main use of a tool or object.
The primary purpose of an umbrella is to keep you dry in the rain.