millionth

American  

[mil-yuhnth] / ˈmɪl yənθ /

adjective

1. coming last in a series of a million.

2. being one of a million equal parts.

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noun

1. the millionth member of a series.

2. a millionth part, especially of one (1/1,000,000).

millionth British  

/ ˈmɪljənθ /

noun

1. 1. one of 1 000 000 approximately equal parts of something

   2. ( as modifier )

      a millionth part

2. one of 1 000 000 equal divisions of a particular scientific quantity

3. the fraction equal to one divided by 1 000 000

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adjective

1. (usually prenominal)

   1. being the ordinal number of 1 000 000 in numbering or counting order, etc

   2. ( as noun )

      the millionth to be manufactured

Etymology

Origin of millionth

First recorded in 1665–75; million + -th ²

Example Sentences

For scale, a nanometer is one millionth of a millimeter.

From Science Daily

For probably the millionth time in my life, I wondered why everyone else got watertight brains, while mine was apparently Swiss cheese.

From Literature

I’m about to tell her—to admit for what feels like the ten millionth time— that I don’t know what that is, when Eddie asks, “What’s a petit four?”

From Literature

It sounds like something from the distant future, but nanotechnology - engineering at a scale of millionths of a millimetre - is already used in lots of everyday real-life tech.

From BBC

A difference of 477 millionths of a second may seem insignificant.

From Science Daily