thousandth

American

[thou-zuhndth, -zuhntth, -zuhnth] / ˈθaʊ zəndθ, -zəntθ, -zənθ /

adjective

last in order of a series of a thousand.
being one of a thousand equal parts.

noun

a thousandth part, especially of one (1/1000).
the thousandth member of a series.
Also thousandth's place (in decimal notation) the position of the third digit to the right of the decimal point.

thousandth British

/ ˈθaʊzənθ /

adjective

(usually prenominal)
1. being the ordinal number of 1000 in numbering or counting order, position, time, etc
2. ( as noun )
  
  the thousandth in succession

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

noun

1. one of 1000 approximately equal parts of something
2. ( as modifier )
  
  a thousandth part
one of 1000 equal divisions of a particular scientific quantity

millivolt
the fraction equal to one divided by 1000 ( 1/ 1000 )

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of thousandth

First recorded in 1545–55; thousand + -th ²

Vocabulary lists containing thousandth

Number and Operations in Base Ten

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Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

It is roughly one thousandth of the time it takes to blink.

From Science Daily • Dec. 30, 2025

Any parent who has read a “Berenstain Bears” book aloud under duress for the thousandth time will know what I mean.

From The Wall Street Journal • Dec. 12, 2025

He was gifted with a superhuman taste sensitivity: He could easily distinguish a flavor at one ten thousandth of a gram in a fifteen ton batch.

From Salon • Nov. 7, 2024

The official margin was a thousandth of a second — every bit as close as the Kentucky Derby a day earlier — and Buescher was left both dumbfounded and dejected.

From Seattle Times • May 5, 2024

She gnawed at her bottom lip as the words crossed her mind for the hundredth time, the thousandth.

From "Beasts of Prey" by Ayana Gray

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023