worsen
/ˈwɜ:sn; `wəsn/ v [I, Tn]
(cause sth to) become worse （使某事物）更坏, 恶化
The patient's condition worsened during the night. 病人的情况在夜间恶化了.
the worsening economic situation 每况愈下的经济形势
The drought had worsened their chances of survival. 出现乾旱後他们就更难活命了.