coreproblem
nounUK /kɔː ˈprɒbləm/
US /kɔːr ˈprɑːbləm/
The main thing that is wrong and needs to be fixed.
The core problem is that the bridge is too old and weak.
OTHER MEANINGS
2. The most basic reason something is not working.
We fixed many small things, but the core problem was still there.
3. The hardest part of a puzzle or task.
Finding the core problem took longer than solving it.
4. The central question in a discussion or study.
The report focuses on the core problem of water shortage.