chiefpurpose
nounUK /tʃiːf ˈpɜːpəs/
US /tʃiːf ˈpɝːpəs/
The main reason you do something.
The chief purpose of a school is to help children learn.
OTHER MEANINGS
2. The most important job or use of a thing.
The chief purpose of this box is to keep toys safe.
3. The biggest reason behind a plan.
Her chief purpose in saving money was to buy a bike.
4. The main point of doing something.
The chief purpose of the game is to have fun.