Merriam-Webster's Advanced Learner's Dictionary:
nineteen
nine·teen /naɪnˈtiːn/ noun, pl -teens [count] : the number 19
- nineteen adj
• nineteen hours
- nineteen pronoun
• She bought nineteen (of them).
- nine·teenth /naɪnˈtiːnɵ/ noun, pl -teenths [count]
• The book is due back on the nineteenth (of the month).
• one nineteenth of the total cost
- nineteenth adj
• He was the country's nineteenth president.
• I was the nineteenth person to cross the finish line.
• (humorous) the nineteenth hole [=the bar at a golf course where players drink after playing a round of 18 holes of golf]
- nineteenth adv
• She finished nineteenth in the race.
• the country's nineteenth largest state
