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.
source: Webster 1913
noun
position 1,000 in a countable series of things
source: WordNet 3.0
one part in a thousand equal parts
source: WordNet 3.0
The quotient of a unit divided by a thousand; one of a thousand equal parts into which a unit is divided.
source: Webster 1913
adjective satellite
the ordinal number of one thousand in counting order