noun, noun or participle which takes 'suru', intransitive verb
deterioration; worsening; aggravation
Used for conditions, situations, relationships, or health becoming worse. Often appears as 悪化する (intransitive) or 悪化させる (transitive).
病状が急に悪化した。
His condition suddenly worsened.
両国
We must not let relations between the two countries deteriorate any further.