The ordinal number matching the number 1,000 in a series.(noun)
One of 1,000 equal parts.(noun)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "thousandth" in a sentence
"It is 0.5 thousandth, that is, half of a thousandth."
"In an instant her mind learns so many things at once that if the imagination and intellect spent years in striving to enumerate them, it could not recall a thousandth part of them."
"The term means "thousandth-part money," that is, the thousandth part of a _tael_ or Chinese ounce of silver, say one _cash_; and it was originally applied to a tax of one _cash_ per tael on all sales, said to have been voluntarily imposed on themselves by the people, as a temporary measure, with a view to make up the deficiency in the land-tax caused by the rebellion."