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Acrimonious became a top lookup on Merriam-Webster on August 30.
Guns 'N Roses guitarist Slash filed for divorce.
In a description widely repeated online, the celebrity news site TMZ.com reported that sources close to the couple described the breakup as "extremely acrimonious."
Acrimonious means harsh or biting, especially in feeling or language. It comes from the Latin word for sharp, which also gives us acrid.