Simple past tense and past participle of buck.(verb)
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Use "bucked" in a sentence
"The train bucked and slowed and his legs gave way and he fell."
"In an era when many young college stars bolt for the NBA after minimal time on campus, the decision by the Gators to return en masse for another crack at a title bucked that trend."
"Milingo bucked the Vatican again in September, when he ordained four married American men as bishops — an act that meant automatic excommunication."