guarantee

American  

[gar-uhn-tee] / ˌgær ənˈti /

noun

1. a promise or assurance, especially 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. an assurance that another’s obligation will be fulfilled, or something presented as such security; guaranty.

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.

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verb (used with object)

guaranteed, guaranteeing

1. to secure, as by giving or taking security.

   A credit card guarantees your reservation at the hotel.

2. to make oneself answerable for (something) on behalf of someone else who is primarily responsible.

   to guarantee the fulfillment of a contract.

3. to undertake to ensure for another, as rights or possessions.

   The Constitution guarantees freedom of religion.

4. to serve as a warrant or guaranty for.

5. to undertake to protect or indemnify.

   to guarantee a person against loss.

6. to undertake (to do something).

   I will guarantee to prove every word I stated.

7. to promise (usually followed by a clause as object).

   I guarantee that I'll be there.

guarantee British  

/ ˌɡærənˈtiː /

noun

1. a formal assurance, esp in writing, that a product, service, etc, will meet certain standards or specifications

2. law a promise, esp a collateral agreement, to answer for the debt, default, or miscarriage of another

3. 1. a person, company, etc, to whom a guarantee is made

   2. a person, company, etc, who gives a guarantee

4. a person who acts as a guarantor

5. something that makes a specified condition or outcome certain

6. a variant spelling of guaranty

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verb

1. (also tr) to take responsibility for (someone else's debts, obligations, etc)

2. to serve as a guarantee for

3. to secure or furnish security for

   a small deposit will guarantee any dress

4. to undertake to protect or keep secure, as against injury, loss, etc

5. to ensure

   good planning will guarantee success

6. (may take a clause as object or an infinitive) to promise or make certain

Usage

What does guarantee mean? A guarantee is a promise or assurance, especially one that is written or legally binding, that something is of a stated quality or will perform as stated, such as a guarantee that a car you purchase will operate correctly. A guarantee is also an assurance of a particular outcome or condition, as in Weather predictions are not guarantees. Weather often changes quickly. To guarantee something is to secure something, as a ticket guarantees entry to a movie showing. As well, to guarantee is to promise to do something, usually by signing a legally binding agreement, as in The company guaranteed me a job when I signed the contract. Example: I guarantee you will love your purchase and will give you a full refund if you don’t.

Other Word Forms

• nonguarantee noun
• preguarantee noun
• quasi-guaranteed adjective
• reguarantee noun
• superguarantee noun
• unguaranteed adjective

Etymology

Origin of guarantee

First recorded in 1670–80; alteration of guaranty

Explanation

To guarantee is to promise or to a make binding agreement. If a baseball player guarantees his team will win the World Series, he better not lead the league in strikeouts. Guarantee is a word that is both a noun and a verb: the noun means "a binding agreement" and the verb is the act of making that agreement. This word seems to have come from garante, the Spanish word for "protect" and it's related to the Old French word warrant, which means "to authorize." Today, we often come across guarantee in advertisements, and you might wonder how they might guarantee to make your social life better if your teeth are whiter!

Example Sentences

Complicating decisions: Hampshire can’t guarantee partner institutions will honor comparable financial-aid packages.

From The Wall Street Journal • Apr. 16, 2026

Jumping ship to a mutual insurance company doesn’t necessarily guarantee a better deal, but it’s a calculation many are weighing as high insurance costs strain budgets that are already feeling the inflation squeeze.

From MarketWatch • Apr. 16, 2026

In 1971, the Supreme Court began to patch this hole in a case called Bivens, approving monetary damages against federal agents who violated the Fourth Amendment’s guarantee against unreasonable search and seizure.

From Slate • Apr. 15, 2026

Indoor events will have a standby line that does not require tickets; however, there is no guarantee you will be seated.

From Los Angeles Times • Apr. 15, 2026

And yeah, okay, those dudes were really on a team, but I guarantee they kept half that money they raised for themselves.

From "We Were Here" by Matt De La Peña

Related Words

• agreement
• assurance
• certificate
• collateral
• contract
• deposit
• insurance
• security
• warranty