Definition of dog day
1a dog days plural : the period between early July and early September when the hot sultry weather of summer usually occurs b : a day in dog days : a hot sultry day
2 dog days plural : a period marked by dull lack of progress the dog days following any major upheaval
Love words? You must — there are over 200,000 words in our free online dictionary, but you are looking for one that’s only in the Merriam-Webster Unabridged Dictionary.
Join MWU now and get access to America’s largest dictionary, with:
- 300,000 words that aren't in our free dictionary
- Expanded definitions, etymologies, and usage notes
- Advanced search features
- Ad free!
Origin and Etymology of dog day
back-formation from dog days, translation of Late Latin dies caniculares, translation of Greek hēmerai kynades; from their being reckoned in ancient times from the heliacal rising of the Dog Star (Sirius)
First Known Use: 1538
Seen and Heard
What made you want to look up dog day? Please tell us where you read or heard it (including the quote, if possible).