millionth
n.the position of number 1,000,000 in a series. It is the ordinal form of the number one million.
n.the ordinal number corresponding to the cardinal number one million. Often used in technical contexts to describe a specific position in a sequence or a fraction of a million.
“He reached the millionth visitor to his website today.”
“The scientist measured the concentration of the substance down to the millionth of a gram to ensure accuracy.”
“In a vast database containing billions of records, the millionth entry was flagged for an anomaly that required manual verification by the engineering team.”
“Her own book, Coat of Many Colours, was the 100 millionth book that programme donated to the US Library of Congress collection.”
From million + -th (ordinal suffix).
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.