This is an adjective.
The noun form is acrimony.
Oxford dictionary defines this word as 'angry and bitter.'
1.The new agriculture policy has generated acrimony among the farmers.
2.The scientist had an acrimonious experience at the meet as he was not allowed to deliver his speech completely.
3.The banks have now decided to increase the working hours which have been opposed by the employees. Their acrimony may result in a strike.