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be undisciplined
be undisciplined 作谓语，强调某人或某群体长期缺乏纪律或自制力，而非某次偶发行为。
The students are undisciplined and often talk during class.
这些学生不守纪律，经常在课堂上讲话。
不遵守纪律的；缺乏纪律的
先理解核心含义，再看它在真实句子里的用法。
不遵守纪律的；缺乏纪律的
not subjected to discipline; lacking discipline
The students are undisciplined and often talk during class.
这些学生不守纪律，经常在课堂上讲话。
不守纪律的；不受约束的；未改正的。
not subjected to discipline, control or correction; uncorrected
未受纪律约束
not subjected to discipline
缺乏自控能力的；难管束的
lacking in self-control; ungovernable
未受纠正或纪律约束
not subjected to correction or discipline
The team lost because their undisciplined defense kept leaving the goal unprotected.
球队输了，因为他们的防守缺乏纪律，总是让球门无人保护。
AI contextual example
My neighbor's dog is undisciplined; it jumps on visitors and ignores every command.
我邻居的狗没有受过训练；它会扑向访客，无视所有指令。
AI contextual example
An undisciplined mind often starts many projects but finishes none.
缺乏条理的思维常常开始许多项目，却一个也完不成。
AI contextual example
undisciplined talent
缺乏纪律的才华。
WordNet
be undisciplined 作谓语，强调某人或某群体长期缺乏纪律或自制力，而非某次偶发行为。
The students are undisciplined and often talk during class.
这些学生不守纪律，经常在课堂上讲话。
作定语时，undisciplined 可修饰人（如 child, troops）或抽象名词（如 mind, imagination），表示“缺乏训练、不受约束”之意。
An undisciplined mind often jumps from one idea to another.
缺乏训练的头脑常常从一个想法跳到另一个想法。
Not this
He behaved undisciplined in class.
Use this
He was undisciplined in class.
“undisciplined”是形容词，只能修饰名词或用在be、seem等系动词后。动词behave是行为动词，需要副词或副词短语修饰，不能直接接形容词。把behaved改成was，用系动词加形容词来描述状态，句子才正确。
Not this
His undisciplined caused him to fail.
Use this
His lack of discipline caused him to fail.
“undisciplined”是形容词，不能直接作主语或宾语。表示“缺乏纪律”这一抽象概念时，要用名词短语lack of discipline或undisciplined behavior。改成lack of discipline后，句子结构才正确。
Focus on the distinctions below. Other candidates are kept compact until a reliable usage note is available.
不守规矩的行为；缺乏纪律的表现
The teacher complained about the undisciplined behaviour of the class.
老师抱怨这个班级不守规矩的行为。
缺乏管教的孩子；不听话的孩子
Raising an undisciplined child requires patience and consistent rules.
养育一个缺乏管教的孩子需要耐心和始终如一的规矩。
缺乏条理的思维；散漫的头脑
An undisciplined mind often jumps from one thought to another.
缺乏条理的思维常常从一个念头跳到另一个念头。
纪律涣散的部队；缺乏训练的军队
Undisciplined troops are unreliable in battle.
纪律涣散的部队在战斗中靠不住。
缺乏章法的方式；随意的做法
His undisciplined approach to studying led to poor results.
他缺乏章法的学习方式导致了糟糕的成绩。
Use undisciplined naturally, then get feedback on meaning, tone, grammar, and phrasing.
Revisit a common error or keep this word in your review list.
记忆：un-（不）+ disciplined（守纪律的）→ 不守纪律的。想象一个不按哨声集合、到处乱跑的学生，就是 undisciplined。
语域：neutral 常见场景：教育、职场、体育 “undisciplined” 属于中性形容词，多用于描述人、行为或思维欠缺纪律、训练或自我约束。在学校、工作和运动等场景中都较常见，语气比日常口语词更正式一些。
只有 disciplined /ˈdɪsɪplɪnd/ 是真正的韵脚，其重读音节 /dɪs/ 后的 /ɪplɪnd/ 与 undisciplined 的 /ənˈdɪsɪplɪnd/ 完全一致；其余都是拼写形近而读音不同：inclined、opined、unlined 的 -ined 读 /aɪnd/，determined 的 -mined 读 /mɪnd/，unprincipled 只共享 un- 前缀。
Dictionary facts from ECDICT, WIKTIONARY.