noun, noun or participle which takes 'suru'
becoming more difficult; increasing difficulty
Often used for exams, tests, or problems that have become harder than before. Can be used as a noun or with する to mean 'to become more difficult'.
今年の試験は難化したと言われている。
It is said that this year's exam became more difficult.
問題の難化に対応
We strengthened our measures to cope with the increasing difficulty of the problems.