Definition of GUARANTEE

1. a promise or assurance, esp. one in writing, that something is of specified quality, content, benefit, etc., or that it will perform satisfactorily for a given length of time: a money-back guarantee. 
2. guaranty (defs. 1, 2). 
3. something that assures a particular outcome or condition: Wealth is no guarantee of happiness. 
4. a person who gives a guarantee or guaranty; guarantor. 
5. a person to whom a guarantee is made. 
–verb (used with object) 6. to secure, as by giving or taking security. 
7. to make oneself answerable for (something) on behalf of someone else who is primarily responsible: to guarantee the fulfillment of a contract. 
8. to undertake to ensure for another, as rights or possessions. 
9. to serve as a warrant or guaranty for. 
10. to engage to protect or indemnify: to guarantee a person against loss. 
11. to engage (to do something). 
12. to promise (usually fol. by a clause as object): I guarantee that I’ll be there. 
[Origin: 1670–80; alter. of guaranty]
Dictionary.com Unabridged (v 1.1)
Based on the Random House Unabridged Dictionary, © Random House, Inc. 2006.

 

Something that assures a particular outcome or condition: Lack of interest is a guarantee of failure.  

A promise or an assurance, especially one given in writing, that attests to the quality or durability of a product or service.
A pledge that something will be performed in a specified manner.
A guaranty by which one person assumes responsibility for paying another’s debts or fulfilling another’s responsibilities.
A guaranty for the execution, completion, or existence of something.

A guaranty by which one person assumes responsibility for paying another’s debts or fulfilling another’s responsibilities.
A guaranty for the execution, completion, or existence of something.
A guarantor.

tr.v.   guar·an·teed, guar·an·tee·ing, guar·an·tees

To assume responsibility for the debt, default, or miscarriage of.
To assume responsibility for the quality or performance of: guarantee a product.
To undertake to do, accomplish, or ensure (something) for another: guaranteed to free the captives; guarantees freedom of speech.
To make certain: The rain guarantees a good crop this year.
To furnish security for.
To express or declare with conviction: I guarantee that you’ll like this book.
[Alteration of Middle English garant, warranty, from Old French; see guaranty.]
The American Heritage® Dictionary of the English Language, Fourth Edition. Published by Houghton Mifflin Company.

 

guarantee  (n.)  

1679, perhaps via Sp. garante, from O.Fr. guarantie, pp. of fem. guarantir “to protect,” from guarant “warrant,” from Frank. *warjand-s, from P.Gmc. *war-, from PIE base *wer- “to cover” (see warrant). For form evolution, see gu-. Originally “person giving something as security,” sense of the “pledge” itself (which is properly a guarranty) first recorded 1786. The verb is attested from 1791.

Online Etymology Dictionary, © 2001 Douglas Harper

 

guarantee  

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

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

WordNet® 3.0, © 2006 by Princeton University.

guarantee1 [garənˈtiː] noun 

guarantee2 [garənˈtiː] noun

guarantee1 [garənˈtiː] verb

guarantee2 [garənˈtiː] verb

Main Entry: gua·ran·tee
Pronunciation: "gar-&n-'tE, "gär-
Function: noun
Etymology: probably alteration of guaranty
1 : GUARANTOR
2 : GUARANTY 1
3 : an assurance that a condition will be fulfilled: as a : an agreement by which one person undertakes to secure another in the possession or enjoyment of something b : an assurance of the quality or of the length of use to be expected from a product offered for sale often with a promise of reimbursement
4 : GUARANTY 4, 5 guarantees> —guarantee transitive verb 

Guarantee  

Guar`an*tee”\, n.; pl. Guarantees. [For guaranty, prob. influenced by words like assignee, lessee, etc. See Guaranty, and cf. Warrantee.]

1. In law and common usage: A promise to answer for the payment of some debt, or the performance of some duty, in case of the failure of another person, who is, in the first instance, liable to such payment or performance; an engagement which secures or insures another against a contingency; a warranty; a security. Same as Guaranty.

His interest seemed to be a guarantee for his zeal. –Macaulay.

2. One who binds himself to see an undertaking of another performed; a guarantor. –South.

Note: Guarantor is the correct form in this sense.

3. (Law) The person to whom a guaranty is made; — the correlative of guarantor.

Syn: Guarantee, Warranty.

Usage: A guarantee is an engagement that a certain act will be done or not done in future. A warranty is an engagement as to the qualities or title of a thing at the time of the engagement. Webster’s Revised Unabridged Dictionary, © 1996, 1998 MICRA, Inc.