"defeat sb."是动词短语，意为“击败某人；战胜某人；使某人失败”，强调在竞争、对抗或冲突中通过实力、策略等让对方无法达成目标（如赢比赛、实现计划等）。
直接接人或团队作宾语（不能接“比赛、奖项”等抽象事物，这是与"win"的关键区别）。
The champion defeated his challenger easily.（冠军轻松击败了挑战者。）
Our team defeated the rivals in the final.（我们队在决赛中战胜了对手。）
通过“in + 具体领域/活动”补充击败对方的场景（如比赛、辩论、选举等），是最常用的扩展结构。
She defeated me in the spelling bee.（她在拼字比赛中击败了我。）
The candidate defeated his opponent in the presidential election.（这位候选人在总统选举中战胜了对手。）
表示“被某人击败”，强调动作的承受者。
I was defeated by her in the chess game.（我在象棋比赛中被她击败了。）
The enemy army was defeated by our troops.（敌军被我们的部队击败了。）
除了体育/竞技，还可用于战争、辩论、职场竞争等场景，只要涉及“对抗中的胜利”：
战争：The allied forces defeated the axis powers in WWII.（盟军在二战中击败了轴心国。）
辩论：The lawyer defeated the witness with solid evidence.（律师用确凿的证据驳倒了证人。）
defeat vs. beat：都可表示“击败人”，但"defeat"更正式（多用于书面/严肃场景），"beat"更口语化（日常对话常用）。
He beat me at basketball.（口语）= He defeated me in basketball.（正式）
defeat vs. win："win"后接比赛、奖项、目标（如win the game/win a prize），"defeat"后接人或团队（不能说"win sb."）。
过去式/过去分词：defeated（规则动词）
They defeated us last year, but we’ll get revenge this time.（他们去年击败了我们，但这次我们要复仇。）
现在分词：defeating
The team is defeating all its opponents this season.（这支队伍本赛季击败了所有对手。）
总结："defeat sb."是“击败某人”的标准表达，核心是“对抗中让对方失败”，搭配"in sth."可明确场景，正式语境中常用。