surety
noun /ˈʃʊərəti/,  /ˈʃɔːrəti/
  /ˈʃʊrəti/
[countable, uncountable] (plural sureties)
 (law- money given as a promise that you will pay a debt, appear in court, etc.保证金 - She was granted bail with a surety of $500.她交了 500 美元保证金,获得保释。 
- They have offered a large amount of money as surety.他们提供了一大笔钱作为保证金。 
 
- She was granted bail with a surety of $500.
- a person who accepts responsibility if somebody else does not pay a debt, appear in court, etc.保证人;担保人 - to act as surety for somebody为某人做担保人 
- She has promised to stand surety for £5 000. 她已许诺担保5 000元。 
 
- to act as surety for somebody
词源Middle English (in the sense ‘something given to support an undertaking that someone will fulfil an obligation’): from Old French surte, from Latin securitas, from securus ‘free from care’, from se- ‘without’ + cura ‘care’.