Noun

The process of making or growing worse, or the state of having grown worse.

* {{quote-news

, year=2012 , date=June 4 , author=Lewis Smith , title=Queen's English Society says enuf is enough, innit? , work=the Guardian citation , page= , passage=The Queen may be celebrating her jubilee but the Queen's English Society, which has railed against the misuse and deterioration of the English language, is to fold.}}

Noun

(en noun)

(rare) Bitterness of feeling.

* 1883 , , Mr. Scarborough's Family , ch. 34:

And Dolly's acerbation was aroused by a belief on her part that the money asked for trousers took him generally to race-courses.

* 1963 , Ralph L. Ketcham, "Conscience, War, and Politics in Pennsylvania, 1755-1757," The William and Mary Quarterly , 3rd series, vol. 20, no. 3, p. 425:

As a result of this midwinter acerbation , men on both sides of Philadelphia had ample a reason to feel they contended for nothing less than "the right cause" in the rescue and revival of Britain's imperial destinies.

(rare, medicine) Exacerbation, aggravation, deterioration.Oxford English Dictionary , 3rd ed., 2005.

*2010 , Ewan C. McNay and Victoria E. Cotero, Mini-review: Impact of recurrent hypoglycemia on cognitive and brain function, PubMed Central / US National Library of Medicine :

*:There is, however, significant acerbation of the impact of further episodes of hypoglycemia on cognitive function, so that this risk should be recognized and borne in mind by those receiving or initiating protocols likely to produce such hypoglycemia.