guarantee

A formal promise or assurance; (verb) to make a formal promise that something will happen or be done.

• guarantor/ˌɡærənˈtɔː/(n)担保人
• guaranteed/ˌɡærənˈtiːd/(adj)有保证的；必然的

• money-back guarantee
• guarantee a result
• guarantee quality
• no guarantee
• guarantee success
• unconditional guarantee
• come with a guarantee

1. 1.There's no guarantee that the project will complete on schedule — too many variables are outside our control.
2. 2.The manufacturer guarantees the product for two years against defects in materials or workmanship.

• assure/əˈʃʊə/— make certain; give confidence
• promise/ˈprɒmɪs/— give one's word that something will happen
• warrant/ˈwɒrənt/— officially guarantee

from Spanish "garantia" = warranty, from "garante" (guarantor) — related to Old French "guarantie"