Definition

Noun: - One part in a million equal parts: A unit of measurement representing a single part when a whole is divided into one million (1,000,000) equal parts. It is equivalent to 1/1,000,000 or 0.000001.

Usage

• This term is used to express an extremely small proportion, fraction, or probability.
• It is commonly used in scientific, mathematical, and technical contexts, such as in chemistry (parts per million), engineering, and statistics.

Examples

• The allowed concentration of the contaminant in drinking water is just one-millionth of a gram per liter.
• The device can measure time intervals with an accuracy of one-millionth of a second.
• The chance of that event occurring is less than one-millionth.

Advanced Usage

• As a prefix ('micro-'): In the metric system, the concept of one-millionth is often represented by the prefix (symbol: μ). For example, a is one-millionth of a meter.
• In phrases: The term can be used in the phrase "on the order of one-millionth" to describe the approximate scale of something very small.

Variants and Related Words

• Millionth (noun, adjective): Can be used more generally as the ordinal number (e.g., the millionth visitor) or to mean one of a million equal parts.
• Micro- (prefix): Denoting a factor of one millionth (10⁻⁶).

Synonyms

• One part per million (1 ppm): A common equivalent expression, especially in scientific measurements of concentration or proportion.

Notes

• The term is a specific, numerical concept. It is not typically used in idiomatic expressions or phrasal verbs.
• When used as a noun, it is often followed by "of" (e.g., one-millionth a second).

Noun

1. one part in a million equal parts