chieffunction
nounUK /ˌtʃiːf ˈfʌŋkʃən/
US /ˌtʃif ˈfʌŋkʃən/
The main job that something is made to do.
The chief function of a spoon is to help you eat soup.
OTHER MEANINGS
2. The most important job of a person in a group.
The chief function of the captain is to lead the team.
3. The main thing a machine or tool is built to do.
The chief function of a fan is to move air around.
4. The leading purpose of a part of the body.
The chief function of the heart is to pump blood.