n.

1. 安全，安全感[U]
   Two guards looked after the security of the property.

   两个警卫看管财产的安全。

2. 防备，保安；防护，防御（措施）[U][C][（+against/from）]
   They tightened security during the President's visit.

   他们在总统访问期间加强了安全防卫。

3. 保证；保障；担保（品）[U][C]
   A life-insurance policy may serve as security for a loan.

   人寿保险可作贷款的抵押。

4. 证券，债券[P]
   He traded in securities and became rich.

   他做证券交易发了财。

n.

1. the state of being or feeling secure.
2. the safety of a state or organization against criminal activity such as terrorism.
   ▸measures taken to ensure such safety.
3. a thing deposited or pledged as a guarantee of the fulfilment of an undertaking or the repayment of a loan, to be forfeited in case of default.
4. a certificate attesting credit, the ownership of stocks or bonds, or the right to ownership connected with tradable derivatives.