n.

1. 授权；批准[U]
   He had no warrant for his action.

   他无权那么做。

2. 【律】授权令；逮捕证；搜查证[C]
   The police must obtain a warrant from a judge in order to search a house.

   警察必须从法官处取得搜查证才可搜查房子。

3. （正当）理由，根据[U][（+for）]
   He had no warrant for his suspicion.

   他没有理由那么怀疑。

4. 委任书；委托书；证书；凭单[C]
   Have you got a warrant of fitness for your car?

   你有没有一张汽车合格证书？

5. 证明；保证；诺言[U]

vt.

1. 授权给；批准
2. 使有（正当）理由，成为……的根据[+v-ing]
3. 向……保证，保证（货物）的质量；担保[O8][O5][+（that）]
   The storekeeper warranted the goods as of the first quality.

   店主保证货物品质第一。

4. 【口】断言，敢说[+（that）]

n.

1. an official authorization enabling the police or some other body to make an arrest, search premises, etc.
2. a document entitling the holder to receive goods, money, or services.
3. Finance  a negotiable security allowing the holder to buy shares at a specified price at or before some future date.
4. justification or authority.
5. an official certificate of appointment issued to an officer of lower rank than a commissioned officer.

v.

1. justify or necessitate.
2. officially affirm or guarantee.