dog days

plural noun

Definition of dog days

  1. 1 :  the period between early July and early September when the hot sultry weather of summer usually occurs in the northern hemisphere

  2. 2 :  a period of stagnation or inactivity

dog days was our Word of the Day on 08/12/2010. Hear the podcast!

Did You Know?

Dogs aren’t the only creatures uncomfortable in oppressive heat, so why does a dog get singled out in dog days? The dog here is actually the Dog Star, which is also called Sirius. The star has long been associated with sultry weather in the northern hemisphere because it rises simultaneously with the sun during the hottest days of summer. In the ancient Greek constellation system, this star (called Seirios in Greek) was considered the hound of the hunter Orion and was given the epithet Kyon, meaning "dog." The Greek writer Plutarch referred to the hot days of summer as hēmerai kynades (literally, "dog days"), and a Latin translation of this expression as dies caniculares is the source of our English phrase.

Origin and Etymology of dog days

from their being reckoned from the heliacal rising of the Dog Star (Sirius)

First Known Use: 1538

Other Climate/Meteorology Terms

DOG DAYS Defined for English Language Learners

dog days

plural noun

Definition of dog days for English Language Learners

  • : the hottest time of the year

DOG DAYS Defined for Kids

dog days

noun plural

Definition of dog days for Students

  1. :  the hot period between early July and early September

History for dog days

The brightest star in the sky is Sirius, also known as the Dog Star. Sirius was given this name by the ancients because it was considered the hound of the hunter Orion, whose constellation was nearby. The Dog Star was regarded by the ancient Greeks as the bringer of scorching heat, because its early-morning rising coincided with the hottest summer days of July and August. The Greek writer Plutarch called this time hēmerai kynades, literally, “dog days”—the days of the Dog Star—and by way of Latin this phrase was translated into English as dog days.

Learn More about dog days

Seen and Heard

What made you want to look up dog days? Please tell us where you read or heard it (including the quote, if possible).


a rounded knoll or a ridge of ice

Get Word of the Day daily email!


Take a 3-minute break and test your skills!

Name That Thing

Test your visual vocabulary with our 10-question challenge!


Test Your Knowledge - and learn some interesting things along the way.