challenge , dispute , gainsay (verb) - take exception to; "She challenged his claims"
quarrel , dispute , scrap , argufy , altercate (verb) - have a disagreement over something; "We quarreled over the question as to who discovered America"; "These two fellows are always scrapping over something"
dispute , difference , difference of opinion , conflict (noun) - a disagreement or argument about something important; "he had a dispute with his wife"; "there were irreconcilable differences"; "the familiar conflict between Republicans and Democrats"
dispute , contravention (noun) - coming into conflict with