position 19 in a countable series of things
"The nineteenth letter on the alphabet is S."
The person or thing in the nineteenth position.
"The nineteenth runner crossed the finish line just ahead of the twentieth."
In plain English: The nineteenth is the number that comes right after eighteen and before twenty.
"She is the nineteenth person to sign up for the club today."
coming next after the eighteenth in position
"The nineteenth item on the list was finally checked off."
The ordinal form of the number nineteen.
"She was born in the nineteenth century, but her favorite year is simply 1905."
In plain English: Nineteenth means coming after eighteen and being the last number before twenty.
"She was born on her nineteenth birthday in 2015."
Usage: Use "nineteenth" as an adjective to describe something that holds the specific rank of 19 within a sequence, such as the nineteenth chapter of a book. It is distinct from "nine," which refers only to the quantity without implying order or position.
The word nineteenth is formed by adding the ordinal suffix "-th" to the number nineteen. This straightforward construction follows the standard pattern used to create numbers ending in nine.