Millennium
A millennium was a time period of one thousand years.

In 2000, Henry Janeway expressed his belief that he'd been born in the wrong millennium. He expressed more of an interest in the classical age than the modern age. ()

In 2365, after obtaining an Iconian artifact containing unintelligible starfields, 200 millennia of stellar drift were taken into account to help pinpoint the location of the planet Iconia. ()

According to Lieutenant Commander Data later that year, true fossilization required several millennia. ()

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Time measurements