seal the deal

American  

[seel thuh deel] / ˈsil ðə ˈdil /

Also close the deal

idiom

1. to complete or successfully negotiate an agreement.

   If our top executive can't seal the deal, no one can.

2. to secure or ensure a successful conclusion: A last-minute goal sealed the deal for Baltimore.

   He had aced both interviews, and if the director liked him that would seal the deal.

   A last-minute goal sealed the deal for Baltimore.

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Etymology

Origin of seal the deal

First recorded in 1950–55

Example Sentences

They showed off T-shirts saying "Seal the deal" during an ovation for the Israeli leader and were arrested for an unlawful demonstration.

From BBC

That the film contains one of the year’s finest performances may seal the deal for more serious viewers.

From Los Angeles Times

She and husband Chris were the first people to view the property in July after travelling 130 miles from their home in Tamworth, Staffordshire, to seal the deal within 48 hours.

From BBC

And unlike the vote on that earlier compensation package, Elon and Kimbal Musk will both get to vote as they push to reach the majority threshold required to seal the deal.

From BBC

Donna Langley, chairman of NBCUniversal Entertainment, who was heavily involved in wooing Sheridan to Universal over the past two months, made a pilgrimage to his ranch to help seal the deal.

From The Wall Street Journal