We found 15 dictionaries that define the word day in day out:

General (14 matching dictionaries)

1. day in, day out: Merriam-Webster
2. day in, day out: Oxford Learner's Dictionaries
3. day in, day out, day in, day out: Collins English Dictionary
4. day in day out: Vocabulary.com
5. day in, day out: Wordnik
6. day in day out: Cambridge Advanced Learner's Dictionary
7. Day in, day out, day in, day out, day in day out: Dictionary.com
8. Day-In Day-Out, Day In Day Out (Feeder song): Wikipedia, the Free Encyclopedia
9. day in day out: Rhymezone
10. day in day out: FreeDictionary.org
11. day in day out: Mnemonic Dictionary
12. Day in, day out, day in day out: TheFreeDictionary.com

Miscellaneous (1 matching dictionary)

13. day in, day out: Idioms

Definitions from WordNet (day in day out) ▸ adverb:  for an indefinite number of successive days Opposite: sporadic, intermittent, irregular, occasional Phrases: day in and day out, more... ▸ Words similar to day in day out ▸ Usage examples for day in day out ▸ Idioms related to day in day out ▸ Wikipedia articles (New!) ▸ Words that often appear near day in day out ▸ Rhymes of day in day out ▸ Invented words related to day in day out