Social Security number

American  

[soh-shuhl si-kyoor-i-tee nuhm-ber] / ˈsoʊ ʃəl sɪˈkyʊər ɪ ti ˌnʌm bər /

noun

1. a unique nine-digit number assigned to each U.S. citizen and sometimes also given to resident non-citizens, used by the government for Social Security taxes, program eligibility, etc. SSN

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Etymology

Origin of Social Security number

First recorded in 1935–40

Example Sentences

Babies born from 2025 to 2028 who are American citizens and have a Social Security number are eligible for the seed money.

From Barron's • May 28, 2026

Make sure your voter registration is current by entering your name, date of birth and identification or Social Security number on the secretary of state’s website.

From Los Angeles Times • May 1, 2026

A secure portal also beats emailing documents directly to your preparer, since forms often include your Social Security number and other sensitive financial information.

From MarketWatch • Apr. 1, 2026

In addition, make sure your name, tax year and Social Security number are on the reply.

From The Wall Street Journal • Mar. 20, 2026

Instead of merely listing the name of each dependent child, tax filers were now required to provide a Social Security number.

From "Freakonomics: A Rogue Economist Explores the Hidden Side of Everything" by Steven D. Levitt