/ ˈʃʊərəti; ˈʃɔːr-; NAmE ˈʃʊr-/ noun [ C , U ] ( pl. -ies ) ( law )
1.
money given as a promise that you will pay a debt, appear in court, etc. :
She was granted bail with a surety of $500.
2.
a person who accepts responsibility if sb else does not pay a debt, appear in court, etc. :
to act as surety for sb
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WORD ORIGIN
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.