thousand
n.the number 1,000. You use it to talk about a large group of people or things.
n.the cardinal number equal to ten times one hundred. Often used figuratively to indicate a large but unspecified quantity.
“There are one thousand meters in a kilometer.”
“The stadium was packed with over ten thousand fans cheering for the home team.”
“The ancient ruins have stood for several thousand years, surviving countless wars and natural disasters while remaining largely intact for modern archaeologists to study.”
When used as a specific number with another digit, it remains singular ('two thousand'); it becomes plural ('thousands') when used to describe an indefinite large amount.
When preceded by a specific number, 'thousand' does not take a plural 's'.
Usage thousands of people · thousands of years · thousands of miles
From Middle English thousend, thusand, from Old English þūsend (“thousand”), from Proto-West Germanic þūsundi, from Proto-Germanic þūsundī (“thousand”), (compare Scots thousand (“thousand”), Saterland Frisian duusend (“thousand”), West Frisian tûzen (“thousand”), Dutch duizend (“thousand”), German tausend (“thousand”), Danish tusind (“thousand”), Swedish tusen (“thousand”), Norwegian tusen (“thousand”), Icelandic þúsund (“thousand”), Faroese túsund (“thousand”)), from Proto-Indo-European tuHsont-, tuHsenti- (compare Lithuanian tūkstantis (“thousand”), Polish tysiąc, Russian ты́сяча (týsjača), Finnish tuhat, Estonian tuhat).
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.