seventeenth

seven·teenth [seventeenth seventeenths] [ˌsevnˈtiːnθ] ; [ˌsevnˈtiːnθ] ordinal number, noun There are examples of how to use ordinal numbers at the entry for fifth.

Main entry: seventeen

Cambridge Advanced Learner's Dictionary

Cambridge Advanced Learner's Dictionary - 4th Edition

seventeenth / ˌsev. ə nˈtiːnθ / ordinal number

17th written as a word:

My mother's birthday is on the seventeenth ( of June).

Collins COBUILD Advanced Learner’s English Dictionary

seventeenth

[se̱v(ə)nti͟ːnθ]
♦♦
seventeenths
1) ORD The seventeenth item in a series is the one that you count as number seventeen.
She gave birth to Annabel just after her seventeenth birthday.
2) FRACTION A seventeenth is one of seventeen equal parts of something.

Merriam-Webster's Advanced Learner's Dictionary

Merriam-Webster's Advanced Learner's Dictionary:

seventeen

sev·en·teen /ˌsɛvənˈtiːn/ noun, pl -teens [count] : the number 17
- seventeen adj
• They lived together for seventeen years.
- seventeen pronoun
• We interviewed seventeen (of them).
- sev·en·teenth /ˌsɛvənˈtiːnɵ/ noun, pl -teenths [count]
• I'll see you on the seventeenth of April.
• The bill is due on the seventeenth (of the month).
• one seventeenth of the total
- seventeenth adj
• The paintings were made in the seventeenth century.
• He finished in seventeenth place.
- seventeenth adv
• She finished seventeenth in the race.