(US, modern British & Australian, short scale) A billion billion: 1 followed by eighteen zeros, 10¹⁸. / (dated, British & Australian, long scale) A million quadrillion: 1 followed by 30 zeros, 10³⁰.

(figuratively, slang, hyperbolic) Any very large number, exceeding normal description.

plural of quintillion

The ordinal form of the number one quintillion.

The person or thing in the quintillionth position. / One of a quintillion equal parts of a whole.

(rare) By a multiple of one quintillion; by a quintillion times as much or as many.

(rare) By a factor of one quintillion.

plural of quintillionth

Somebody whose wealth is greater than one quintillion units of the local currency.

plural of quintillionaire