Contentious describes something that is likely to cause people to argue or disagree or that involves a lot of arguing. When used of a person, contentious describes someone likely or willing to argue.

// I think it’s wise to avoid such a contentious topic at a dinner party.

// After a contentious debate, members of the committee finally voted to approve the funding.

// The dispute involves one of the region’s most contentious leaders.

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“Next up will be Peter Shaffer’s ‘Amadeus,’ which opened in 1979 and won the Tony for best play in 1981 with Ian McKellen winning lead actor honors. ... The story is a fictional account of the contentious relationship between Wolfgang Amadeus Mozart and his rival, Antonio Salieri, the court composer of the Austrian emperor.” — Jessica Gelt, The Los Angeles Times, 12 June 2025

If everyone has a bone to pick now and then, contentious types have entire skeletons. While English has plenty of words for people prone to fighting—combative and belligerent among them—contentious implies a fondness for arguing that others find particularly tedious or wearying. Thankfully, even the most contentious cranks and crabs among us have no cause to quibble over the history of the word contentious, as its origins are very clear: contentious comes (by way of Middle French) from the Latin adjective contentiōsus, meaning “persistent, obstinate, argumentative, or quarrelsome.”