guarantee in WordNet English dictionary

1. make certain of
   "This nest egg will ensure a nice retirement for us"; "Preparation will guarantee success!"
   guarantee  ensure  insure  assure  secure 
   
2. give surety or assume responsibility
   "I vouch for the quality of my products"
   guarantee  vouch 
   
3. promise to do or accomplish
   "guarantee to free the prisoners"
   undertake  guarantee 
   
4. stand behind and guarantee the quality, accuracy, or condition of
   "The dealer warrants all the cars he sells"; "I warrant this information"
   guarantee  warrant 
   

1. a written assurance that some product or service will be provided or will meet certain specifications
   guarantee  warrant  warrantee  warranty 
   
2. an unconditional commitment that something will happen or that something is true
   "there is no guarantee that they are not lying"
   guarantee 
   
3. a collateral agreement to answer for the debt of another in case that person defaults
   guarantee  guaranty