insane

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

  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 本词

  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: extremely foolish or unreasonable (adjective).

比较义项：极其愚蠢，不合情理（adj.）。

• insane 本词

  Informal, hyperbolic intensifier for reckless or extreme foolishness, often about dangerous actions or ideas; stronger than silly or ridiculous and not meant literally about mental illness.

  口语化的夸张说法，形容鲁莽或极端的愚蠢，多用于描述危险的行为或想法；语气比 silly 和 ridiculous 都强，并非字面指精神失常。

  Skydiving without checking your parachute twice is insane.

  没把降落伞仔细检查两遍就跳伞，简直太insane了。

• silly

  Mild and often affectionate, describing a small, sometimes childish lack of good sense; the weakest in strength, used for minor mistakes or playful behavior rather than serious risk.

  语气温和，有时带亲切感，形容轻微、常带孩子气的不明智；三者中语气最弱，多用于小错误或调皮行为，而非严重的风险。

  Sorry, that was a silly mistake — I forgot my keys again.

  抱歉，这是个silly的小错误——我又忘记带钥匙了。

• ridiculous

  Emphasizes that something is so foolish or unreasonable it deserves mockery, often applied to situations, demands, prices or rules rather than a person's actions.

  强调某事愚蠢或不合情理到该被嘲笑的地步，常用来评价情况、要求、价格或规定，而不是某人具体的行为。

  Charging ten dollars for a bottle of water is ridiculous.

  一瓶水收十美元，简直ridiculous。

All three describe something extremely foolish. Insane is informal and hyperbolic, the strongest. Silly is the mildest, often a small, childish mistake. Ridiculous stresses something is so unreasonable it deserves mockery, for situations, demands, or prices. Excludes insane meaning 'mentally ill'.

这三个词都能形容“愚蠢到可笑或不合情理”的程度，但语气强弱和使用场合不同：insane 语气最强，带夸张的口语色彩，常形容鲁莽的行为或想法；silly 语气最轻，多形容孩子气或无关紧要的小错误；ridiculous 强调“荒谬到该被嘲笑”，常用来评价情况、要求或价格是否合理。这里不比较 insane 表示“精神失常的”的义项。