fifteenth

fif·teenth [fifteenth fifteenths] [ˌfɪfˈtiːnθ] ; [ˌfɪfˈtiːnθ] ordinal number, noun There are examples of how to use ordinal numbers at the entry for fifth.

Main entry: fifteen

Cambridge Advanced Learner's Dictionary

Cambridge Advanced Learner's Dictionary - 4th Edition

fifteenth / ˌfɪfˈtiːnθ / ordinal number

15th written as a word:

Today is the fifteenth ( of June).

Collins COBUILD Advanced Learner’s English Dictionary

fifteenth

[fɪ̱fti͟ːnθ]
♦♦
ORD
The fifteenth item in a series is the one that you count as number fifteen.

Merriam-Webster's Advanced Learner's Dictionary

Merriam-Webster's Advanced Learner's Dictionary:

fifteen

fif·teen /ˌfɪfˈtiːn/ noun, pl -teens [count] : the number 15
- fifteen adj
• fifteen dollars
- fifteen pronoun
• Only fifteen (of them) showed up on time.
- fif·teenth /ˌfɪfˈtiːnɵ/ noun, pl -teenths [count]
• the fifteenth of September
• one fifteenth of the total
- fifteenth adj
• the fifteenth day
- fifteenth adv
• Their boat finished fifteenth.