mainstay
noun /ˈmeɪnsteɪ/
/ˈmeɪnsteɪ/
[usually singular]- mainstay (of something) a person or thing that is the most important part of something and enables it to exist or be successful
- He is the mainstay of our theatre group.
- Cocoa is the country's economic mainstay.
- Love songs form the mainstay of his act.