backbone

noun
1
the row of small bones that are connected together down the middle of the back
ستون فقرات, ستون مهره‌ها
synonym spine
2
the most important part of a system, an organization, etc. that gives it support and strength
ستون اصلی, شالوده, پایه و اساس, زیربنا
Agriculture forms the backbone of the rural economy.
3
the strength of character that you need to do something difficult
پشتکار, شجاعت, استقامت, اراده قوی, صلابت
He doesn't have the backbone to face the truth.