Definition

1. Noun:
   • One part in a quintillion equal parts: A unit of measurement representing a single part when a whole is divided into one quintillion (1,000,000,000,000,000,000 or 10^18) equal parts.

Usage

• This term is used in contexts requiring extreme precision in measuring or describing very small proportions, typically in scientific fields like physics, chemistry, and mathematics.
• It functions as a specific fractional noun, often preceded by a cardinal number (e.g., ).

Examples

• Noun:
  • The concentration of the rare isotope in the sample was estimated to be a few one-quintillionth of the total mass.
  • In this theoretical model, the probability of that event occurring is less than one one-quintillionth.

Advanced Usage

• As a numerical prefix: The concept is related to the SI prefix , which denotes a factor of 10^-18. For example, an is one quintillionth of a meter.
  • They measured the displacement in attometers, or one-quintillionths of a meter.

Variants and Related Words

• Quintillionth (noun, adjective): Can be used interchangeably with "one-quintillionth" as a noun (e.g., ) or as an ordinal number (e.g., ).
• Attosecond (noun): One quintillionth of a second.
• Attogram (noun): One quintillionth of a gram.

Synonyms

• 10^-18: The scientific notation equivalent.
• An atto- unit: When combined with a base unit (e.g., attosecond, attogram).

Notes

• This is a highly specialized term. In most non-scientific contexts, phrases like "an infinitesimally small part" or "a vanishingly small fraction" are more common.
• The word is a compound formed from the cardinal number and the suffix , which is used to form ordinal numbers and fractions.

Noun

1. one part in a quintillion equal parts