Nineteenth means number nineteen in a sequence or order. If you're the nineteenth person in line for lunch, eighteen people are ahead of you. The nineteenth century refers to the years 1801 through 1900, a time when railroads spread across continents, the telegraph revolutionized communication, and many nations abolished slavery.

When you divide something into nineteen equal parts, each piece is called one nineteenth of the whole. If nineteen friends share a pizza equally, each person gets one nineteenth of it.

The word works like other ordinal numbers: first, second, third, and so on up to nineteenth and beyond. You might read the nineteenth chapter of a book, celebrate someone's nineteenth birthday, or learn about the Nineteenth Amendment to the U.S. Constitution, which guaranteed women the right to vote. The spelling can be tricky because you keep the “e” from nineteen but add “th” at the end.