guarantee /ˌɡæɹ.ənˈtiː/noun 5verb 3forms 3 noun5 •something that makes a particular result certainCan you give me a guarantee that he will be fit for the match? •A legal assurance of something, e.g. a security for the fulfillment of an obligation. •A written declaration that a certain product will be fit for a purpose and work correctly; a warranty.The cooker comes with a five-year guarantee. •(informal) A person who gives such a guarantee; a guarantor.But God who is the great Guarantee for the Peace , Order , and good behaviour of Mankind — 1692 •The person to whom a guarantee is made. verb3 •To give an assurance that something will be done right. •To make something certain.The long sunny days guarantee a good crop. •To assume or take responsibility for a debt or other obligation. formsguaranteed · guaranteeing · guarantees