guarantee

noun

• 1a formal promise or assurance (typically in writing) that certain conditions will be fulfilled, especially that a product will be repaired or replaced if not of a specified quality and durability:we offer a 10-year guarantee against rusting
• something that gives a certainty of outcome:past performance is no guarantee of future results

• 2 (also guaranty) Law a formal pledge to pay another person’s debt or to perform another person’s obligation in the case of default.
• a thing serving as security for a formal pledge to pay another person’s debt.
• less common term for guarantor.

verb (guarantees, guaranteeing, guaranteed)

• provide a formal assurance or promise, especially that certain conditions shall be fulfilled relating to a product, service, or transaction: [with clause or infinitive]:the con artist guarantees that the dirt pile will yield at least 20 ounces of gold
• [with object] provide a formal assurance regarding (something, especially a product):the repairs will be guaranteed for three years (as adjective guaranteed)the guaranteed bonus is not very high
• [with object] provide financial security for; underwrite:a demand that $100,000 be deposited to guarantee their costs
• [with object] promise with certainty:no one can guarantee a profit on stocks