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.

ˈthousandth 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

In this environment, the sediment layer grows at a rate of just one thousandth of a millimeter per year.

From Science Daily • Feb. 2, 2026

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

The two British athletes crossed the line together in four minutes 08.45 seconds, but it was Walcott-Nolan who was awarded her first international medal by one thousandth of a second.

From BBC • Mar. 7, 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

We weren’t, and for the forty thousandth time in the last two days, I went over it all again.

From "Tradition" by Brendan Kiely