keydifficulty
nounUK /ˌkiːˈdɪfɪkəlti/
US /ˌkiːˈdɪfɪkəlti/
The main hard thing that makes a job tough.
The key difficulty in the game is the last level.
OTHER MEANINGS
2. The most important trouble in a plan.
The key difficulty with our trip is the weather.
3. The hardest part of learning something.
The key difficulty in math is word problems.
4. The main reason something is not easy.
The key difficulty is that we have no map.