·noun The quotient of a unit divided by a thousand; one of a thousand equal parts into which a unit is divided.
II. Thousandth ·adj Constituting, or being one of, a thousand equal parts into which anything is divided; the tenth of a hundredth.
III. Thousandth ·adj 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.
IV. Thousandth ·adj 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.