worsen

verb

1. (transitive)To make worse; to impair.

   “Near-synonyms: aggravate, exacerbate; degrade, deteriorate; see also Thesaurus:aggravate”

   “Global warming has worsened the weather.”

   “As for further retaliation: adding such fuel to the fire, as it were, will only worsen the already unpleasant state of affairs.”

   “It is apparent that, in the particular point of which we have been conversing, their condition is greatly worsened.”

2. (intransitive)To become worse; to get worse.

   “The weather has worsened.”

   “During the day conditions worsened quickly—for example, a 2-6-0 on the Uckfield line suddenly encountered flood water high enough to enter its ashpan and extinguish its fire—until lock gates up-river at Barcombe gave way and a tidal wave rolled down the valley meeting head-on a spring tide rolling up from the coast.”

   “TPE's cancellation score worsened from 7.2% to 23.8% when adjusted to include pre-cancellations (P*-coded) owing to a shortage of train crew.”

3. (obsolete, transitive)To get the better of; to worst.