billionaire

American

[bil-yuh-nair, bil-yuh-nair] / ˌbɪl yəˈnɛər, ˈbɪl yəˌnɛər /

noun

a person who has assets worth a billion or more dollars, euros, etc.

billionaire British

/ ˌbɪljəˈnɛə /

noun

a person whose assets are worth over a billion of the monetary units of his country

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of billionaire

First recorded in 1855–60, billion + -aire, on the model of millionaire

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

Jim Walton’s net worth as of March 31 was $146 billion, ranking him the eighth wealthiest billionaire in the world, while Rob Walton’s net worth was $143 billion, ranking him No. 10, Bloomberg said.

From Barron's • Apr. 1, 2026

The previous largest donation to a university was in 2019, when American billionaire Stephen Schwarzman donated £185m to Oxford University.

From BBC • Mar. 31, 2026

Her plot-rich story includes art terrorists, undercover agents, snooty Parisians, sneaky New Yorkers and a one-armed billionaire.

From The Wall Street Journal • Mar. 30, 2026

Rep. Katie Porter led at about 16%, followed by Republican Steve Hilton at 13% and billionaire Tom Steyer at 12%.

From Los Angeles Times • Mar. 30, 2026

“I’ve gotten seven marriage proposals! One guy claims to be a billionaire Arab prince.”

From "Small Steps" by Louis Sachar

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023