1
- mass noun care taken to avoid danger or mistakes小心, 谨慎：
anyone receiving a suspect package should exercise extreme caution.
任何人收到可疑包裹时都应极其谨慎。
1.1
- count noun chiefly Brit. an official or legal warning given to someone who has committed a minor offence but has not been charged, to the effect that further action will be taken if they commit another such offence〈主英〉警告（对犯轻罪但未被指控的官方或司法警告, 大意为如再犯将对之采取进一步行动）：
they let him off with a caution.
他们警告他一番后, 就把他放了。
1.2
- warning告诫：
business advisers have sounded a note of caution.
企业顾问们已发出警告。
2
- informal, dated an amusing or surprising person〈非正式, 旧〉可笑的人, 令人吃惊的人。
reporting verb
1- say something as a warning警告：
with clause the Chancellor cautioned that economic uncertainties remained财政大臣警告道, 经济上的不确定因素依然存在
with direct speech 'Be careful now, ' I cautioned.“现在得小心点。”我警告道。
1.1
- no obj.
caution against
warn or advise against (doing something)告诫（或建议）不做（某事）： advisers have cautioned against tax increases.
顾问们告诫不要增税。
1.2
- with obj.（常作be cautioned）chiefly Brit. issue an official or legal warning to〈主英〉发出官方（或司法）警告：
he was cautioned for possessing drugs.
他因拥有毒品而受到警告。
1.3
- with obj.(of a police officer) advise (someone) of their legal rights when arresting them（警官逮捕某人时）提醒（被捕人）所拥有的法律权利。
短语
err on the side of caution
- take a comparatively safe course of action when presented with a choice宁求稳妥, 不愿涉险。
throw caution to the wind（或winds）
- act in a completely reckless manner不顾一切; 鲁莽行事。
under caution
- having been told of one's legal rights when under arrest（被逮捕时）被告知其法律权利。
词源
Middle English （denoting bail or a guarantee; now chiefly Scots and US）： from Latin cautio（n-）， from cavere 'take heed'.