thousandth

American  

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

adjective

1. last in order of a series of a thousand.

2. being one of a thousand equal parts.

---

noun

1. a thousandth part, especially of one (1/1000).

2. the thousandth member of a series.

3. Also thousandth's place (in decimal notation) the position of the third digit to the right of the decimal point.

thousandth British  

/ ˈθaʊzənθ /

adjective

1. (usually prenominal)

   1. being the ordinal number of 1000 in numbering or counting order, position, time, etc

   2. ( as noun )

      the thousandth in succession

---

noun

1. 1. one of 1000 approximately equal parts of something

   2. ( as modifier )

      a thousandth part

2. one of 1000 equal divisions of a particular scientific quantity

   millivolt

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

Etymology

Origin of thousandth

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

Example Sentences

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

In the Milky Way, only the central nucleus has star densities remotely comparable, and that region still contains only about one thousandth of the stars needed for the little-red-dot models.

From Science Daily • Nov. 29, 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

A millisecond is a thousandth of a second.

From BBC • Jul. 22, 2024

So I looked him over as Patrick acknowledged for the thousandth time his ball-lessness etc., and soon it was a staring contest.

From "The Fault in Our Stars" by John Green