We found 23 dictionaries that define the word new year's day:

General (19 matching dictionaries)

1. New Year's Day: Merriam-Webster
2. New Year's Day: Oxford Learner's Dictionaries
3. New Year's Day: American Heritage Dictionary of the English Language
4. New Year's Day, New Year's Day: Collins English Dictionary
5. New Year's Day: Vocabulary.com
6. New Year's Day: Wordnik
7. New Year's Day, New Year's day: Cambridge Advanced Learner's Dictionary
8. New Year's Day: Wiktionary
9. New Year's Day: The Wordsmyth English Dictionary-Thesaurus
10. New Year's Day: Infoplease Dictionary
11. New Year's Day, new year's day, new years day: Dictionary.com
12. New Years Day (EP), New Years Day (band), New Year's Day, New Year's Day (Fear Itself), New Year's Day (Fear Itself episode), New Year's Day (Taylor Swift song), New Year's Day (U2 song), New Year's Day (disambiguation), New Year's Day (horse), New Years Day, New year's day: Wikipedia, the Free Encyclopedia
13. New Year's Day: Online Plain Text English Dictionary
14. New year's day: Rhymezone
15. New Year's Day: AllWords.com Multi-Lingual Dictionary
16. new years day: FreeDictionary.org
17. new year's day: Mnemonic Dictionary
18. New Year's Day, New Years Day: TheFreeDictionary.com
19. New Years Day: Dictionary of Phrase and Fable (1898)

Computing (1 matching dictionary)

20. New Year's Day, New Years' Day, New Years Day: Encyclopedia

Miscellaneous (1 matching dictionary)

21. New Year's Day: Holidays Around the World

Religion (1 matching dictionary)

22. New Year's Day: Catholic Encyclopedia

Slang (1 matching dictionary)

23. New Year's Day, new years day: Urban Dictionary

Definitions from Wiktionary (New Year's Day) ▸ noun:  A holiday celebrating the first day of the New Year, celebrated on January 1 in cultures following the Gregorian calendar. ▸ Words similar to new year's day ▸ Usage examples for new year's day ▸ Idioms related to new year's day ▸ Wikipedia articles (New!) ▸ Words that often appear near new year's day ▸ Rhymes of new year's day ▸ Invented words related to new year's day