Zillionaire

n.capable, hopefulplayful

What it means

An informally imagined person of enormous wealth.

Reach for it when using humorous exaggeration rather than making a literal financial claim

The fictional zillionaire quietly endowed three neighborhood libraries.

playful
mogul
when conspicuous business influence suits informal prose
not when Mogul can refer to media or entertainment reach without verified wealth.
playful
moneybags
when teasing or critical slang is intentional
not when Moneybags is derisive and should not be applied neutrally to a person.
everyday
tycoon
when business control and success are central
not when A tycoon may be less wealthy and is defined by enterprise.
professional
billionaire
when wealth of at least one billion currency units is factual
not when Billionaire is measurable, whereas zillionaire is comic hyperbole.
professional
ultra-rich person
when plain socioeconomic description is needed
not when The threshold for ultra-rich must be defined, but the phrase avoids imaginary numbers.
formal
plutocrat
when wealth also produces political power
not when A plutocrat's influence, not merely fortune, is the defining concern.
literary
magnate
when command of an industry deserves formal description
not when Magnate points to sector power rather than limitless riches.

fictional zillionaire
The fictional zillionaire financed a garden on the moon.
feel like a zillionaire
Three ripe tomatoes made him feel like a zillionaire.
overnight zillionaire
The comedy follows an overnight zillionaire who cannot operate the mansion.

Zillionaire is hyperbole, not a wealth category. Praise for wealth should not imply moral worth or erase how it was acquired.

The definition and the example on this page are written here. The dictionaries above ground which meaning is being described, not the wording.