Next in order after nine hundred and ninty-nine; coming last of a thousand successive individuals or units; -- the ordinal of thousand; as, the thousandth part of a thing.

Occurring as being one of, or the last one of, a very great number; very small; minute; -- used hyperbolically; as, to do a thing for the thousandth time.

position 1,000 in a countable series of things

the ordinal number of one thousand in counting order