crazy

Compared meaning: mentally ill or acting irrationally (adjective).

比较义项：形容人精神失常、极度不理智或情绪失控（adj.）。

• crazy 本词

  The most common, informal word for being mentally ill or acting irrationally; general and non-clinical, often used casually about ordinary people, not in legal or medical contexts.

  最常用、最口语化的词，指精神失常或行为不理智；泛指、不专业，常用来随口形容普通人，而不用于法律或医学语境。

  My grandfather started acting crazy after the accident, forgetting where he was.

  我爷爷出事故后开始变得神志不清，忘记自己身在何处。

• paranoid

  Describes a narrower symptom: unreasonable suspicion or fear that others intend harm, not general madness or wild behavior.

  指更具体的症状：毫无根据地怀疑或害怕别人要加害自己，而不是泛指发疯或行为狂暴。

  After the break-in, she became paranoid and started checking every window twice a night.

  遭遇入室盗窃后，她变得疑神疑鬼，每晚都要把每扇窗户检查两遍。

• insane

  A stronger and more formal word than crazy, used for serious mental illness, especially in legal or medical settings such as court rulings or hospital diagnoses.

  比 crazy 语气更重、更正式，用于严重的精神疾病，尤其常见于法庭判决或医院诊断等法律、医学语境。

  The judge ruled that the killer was legally insane at the time of the crime.

  法官裁定凶手作案时在法律意义上属于精神失常。

• crazed

  Emphasizes wild, out-of-control behavior in the moment rather than a mental state; almost always placed directly before a noun, as in a crazed fan or a crazed gunman.

  强调当下狂暴、失控的行为，而非精神状态本身，几乎总是直接修饰名词，例如疯狂的粉丝或发疯的持枪歹徒。

  A crazed gunman stormed into the building, shooting wildly in every direction.

  一名情绪失控的持枪者冲进大楼，朝四面八方疯狂开枪。

Crazy, paranoid, insane and crazed describe people acting irrationally. Crazy is the most common, informal word. Paranoid means unreasonable suspicion or fear of others. Insane is stronger, more formal, used in legal or medical settings. Crazed describes wild behavior, placed before a noun.

这几个词都可以形容人精神失常或行为异常，但语气和侧重点不同：crazy 最口语化，程度较轻，泛指不理智的言行；insane 更正式、程度更重，常见于法律或医学语境；paranoid 只针对毫无根据的猜疑和恐惧，并非泛指精神失常；crazed 强调一时情绪失控、行为狂暴，几乎只用来修饰名词。这里不比较 crazy 表示「荒谬的，令人难以置信的」（如 a crazy idea）或 insane 表示「极好的，惊人的」（如 insane talent）等口语引申义。

Compared meaning: enthusiastic, very keen on something (adjective).

比较义项：热情、热衷（形容词）。

• crazy 本词

  Informal, hyperbolic, and used predicatively as 'crazy about' + noun; suggests an intense, almost irrational passion, often about a hobby, trend, or celebrity.

  非正式、语气夸张，常用“crazy about+名词”表示对某事（如爱好、潮流或明星）近乎疯狂的强烈热情。

  She's crazy about K-pop and never misses a new album release.

  她对韩流音乐十分狂热，新专辑发行从不错过。

• warm

  Describes friendly, welcoming enthusiasm shown toward people in social situations, not toward a hobby or activity; used before nouns like 'welcome', 'smile', or 'reception'.

  表示在社交场合中对人表现出的友善、热情，而不是对某项爱好或活动的热衷；常用在“welcome”“smile”“reception”等名词前。

  The mayor gave the visiting delegation a warm welcome at the town hall.

  市长在市政厅热情地欢迎了来访代表团。

• avid

  Formal and used attributively before a noun (an avid reader/collector); describes steady, serious enthusiasm for an ongoing interest or activity, without hyperbole.

  语气正式，常用在名词前作定语（如avid reader/collector），形容对某项长期爱好或活动持续、认真的热情，没有夸张色彩。

  My uncle is an avid collector of vintage stamps and rare coins.

  我叔叔是一位热衷收藏老式邮票和稀有硬币的人。

All three express strong enthusiasm. Crazy is informal, an almost irrational passion for a hobby. Warm shows friendly enthusiasm toward people, not a hobby. Avid is formal, before a noun, showing steady interest in an activity. Excludes crazy as 'mentally ill', warm as 'hot'.

这三个词都能表达强烈的热情，但语气和用法不同：crazy非正式、夸张，强调近乎疯狂的痴迷；warm强调待人友善、热情，用于欢迎、微笑等场合而非某项爱好；avid语气正式，多用于名词前，形容对爱好持续认真的投入。这里不比较crazy表示“疯狂的、精神失常的”的义项，也不比较warm表示“温暖的（温度）”的义项。

Compared meaning: foolish, not sensible or workable (adjective).

比较义项：愚蠢的，不切实际的（形容词）。

• crazy 本词

  Stronger and more informal than impractical; expresses a subjective judgment that an idea or plan is foolish, often with surprise or disbelief, rather than a neutral assessment of feasibility.

  比impractical语气更强烈、更口语化，表达说话者认为某个想法或计划愚蠢的主观判断，常带有惊讶或难以置信的意味，而不是对可行性的中性评估。

  It would be crazy to quit your job without any savings.

  没有存款就辞职，那样做太愚蠢了。

• impractical

  More neutral and formal than crazy; describes a plan or object as unrealistic or not workable for actual use, focusing on feasibility rather than expressing an emotional judgment.

  比crazy更中性、更正式，形容某个计划或事物不现实、不便于实际使用，侧重可行性，而非表达情绪化的评判。

  Wearing high heels to hike is completely impractical.

  穿高跟鞋去远足完全不切实际。

Both words describe an idea as foolish or unrealistic. Crazy is stronger and more informal, expressing surprise that something is so foolish. Impractical is more neutral and formal, focusing on whether something is workable, without judging it as foolish. Excludes crazy meaning 'mentally ill'.

这两个词在“愚蠢的，不切实际的”这一意义上相近，但crazy语气更强烈、更口语化，带有说话者觉得某想法荒唐或难以置信的主观情绪；impractical更中性、正式，侧重某事在现实中行不通或不实用，不一定带有“愚蠢”的评判。这里不比较crazy的“疯狂的，精神失常的”等其他意义。